One person diaper change procedure. Any tips?

Meallen; I'm a nurse and I had a heck of a time explaining this.
Haha. 🤔
A video of "how to" from YouTube.
youtube.com/watch?v=NMlw5dBk9LE

Don't get the pull on type diaper for a bedridden patient. Get the ones with tape tabs. WalMart is probably the cheapest.
*Always have a bed protector pad (either disposable or cloth) under patient in case of accidents! I've had patients pee and poop while the dirty diaper was off but the clean one hadn't been applied yet. 😱
*Put on gloves and get cleaning wipes and bag.
*Undo tapes on both sides of old diaper. (Taking tapes off will often tear the plastic part of the diaper. It's ok, you're going to throw it away anyway.)
There is a line indicator on the outside of the diaper that turns blue if the diaper is wet.
*Pull down and clean patient. Remove diaper, roll up with wipes and put in plastic bag. 
*Roll person onto their side (if you're right handed, roll them onto left side.)
*Position clean diaper from front at abdomen, lift right leg up slightly, pull diaper through then push wing with tab down toward bed at left hip. 
*bring diaper around and to the back.
(If cleaning a woman, ALWAYS wipe down from the pubic area. Don't bring stool up near the vaginal (lips) area. It can cause a bladder infection.)
*Apply right tapes from "wing" to the front of the diaper, roll person to back and a bit to the right to catch the other side of the left "wing" area with tab. Apply tapes to left side.
*Remove gloves, wash hands.

I'm sure the movie explains it better than I did.
Don't be surprised if the first few come out "lopsided" or crooked.
Congratulations;
You have just completed Nursing 101!
It takes a bit of practice.

youtube.com/watch?v=NMlw5dBk9LE This might help. And this, for the bedpad. youtube.com/watch?v=s1NiJOmyaLI
What isn't made clear is that you need to roll the patient before you begin so that you have the dirty bedding rolled up to their back, and then again, so you can put the clean bedding against their back on the other side. Your father may be able to help by pulling and pushing with his right arm. I have done this alone for my daughter when she was a hefty teen, and, with my mother, for my father. Any nurses here could give you a better description.

You are NOT stupid, honey. Just on a learning curve. It will improve with time bettymills.com is the cheapest way to buy briefs with tabs (FitRight is the best in my opinion) that I've come across.
Buy in bulk, extra discount, free shipping.

Roll him on his side, and sure, if he doesn't stay there use a pillow.

There are bed wedges which can help hold him: 
amazon.com/dp/B005KPOFSI/ref=cm_sw_r_sms_awdo_t1_nJItAbZHMVDD3

On the side which is not paralyzed, he might be able to help hold position by grabbing a bed rail/bar once he is on his side. You can get various bars for normal beds, like this:
amazon.com/dp/B005JIJRZ2/ref=cm_sw_r_sms_awdo_t1_BzItAbJXEKVH9

Finally, place a pillow between his knees when you turn him, which is more comfortable.

Tab briefs, NOT the pull ons. I would roll my Mom to the left, roll the used pads up toward and against her, put the fresh one down and roll that toward her, then roll her to the right onto the clean ones and pull the dirty ones out, then smoothing the new ones in place. The videos should help. The key is to roll the patient. This works with slide sheets as well if you need to move the patient up in bed if they slide downward. My Mom was able to grab the side bedrails, but you can bolster the patient with a pillow if necessary to keep them on their side.

Slide sheets are *magic*! You wouldn't believe how much easier they make it to move a person without risking shearing injuries to him or strain on yourself.

For me, the best way to learn is to watch. Can you ask or hire a visiting nurse to show you what to do?

And has anyone mentioned hoists to you? It is possible to change a bed without getting the person out of it but boy! it is hard going, especially for one person.

Agree SueC has a great description. A couple of things I would add would be to watch your body position and use good body mechanics. It is important you protect your back. Remember to raise the bed (if able), if you do not have a bed that can be raised/lowered talk to your insurance group or county worker; use leg muscles not back muscles to do the big moving. When turning your dad, place your hands to support his hip and shoulder. Remember you are important to your dad and need to care for yourself as well as for him.

My husband is close to 350 lbs. and I have to change him by myself. He is able to roll partway to the left, so we do that side first. I strip the sheets and use “flat hands” to push them under him so I can take them off when I roll him onto his right side. I bathe him then as well and wipe down the mattress with disinfectant wipes. I also change the sheets, half the bed at a time. Your efforts don’t have to be by-the-book perfect, as long as he is comfortable.

PLEASE, honey, change your name! How 'bout Sweetgirl74?
You're an angel 😇 for taking on the responsibility of changing a bedridden patient.

If the skin at the diaper area gets red, (both urine and stool can acid burn the skin), clean well then use A and D ointment or Desitin to protect it. They are both real thick and sticky but they sure do a good job of protecting. Definitely use gloves on your hands when applying or you'll go through a dozen paper towels trying to get it off! 😆
Pull gloves off by hooking the end of the glove at the wrist with a finger from the other hand and pull down. The glove will come off inside out. (Just how you want it!) Do the same with the other glove.

Changing sheets really isn't too hard. Undo the old fitted sheet from all corners. Have your dad roll on one side. You can prop him with pillows against his tummy to keep him from falling face down.
Push the old sheet inward, toward his back. Put clean fitted sheet on top and bottom of the side of mattress you're on. Roll the rest of the sheet "backwards" toward you (like a roll). Put it UNDER the old sheet. Also, at this time, put the bedpads or disposable Chux (brand name) on top of the new sheet.
Try to push the new sheet and pad as far under your dad as possible by pushing into the center of the mattress.

Now, you need to roll your dad to the opposite side. He will have to roll over the "hump" of old and new sheets. Place pillows for stability. Go to the other side and pull dirty sheet out. Put it on floor for now. The new sheet and pad will come along with it. Attach fitted part of new sheet to top and bottom of mattress. Straighten out everything. Wrinkles are uncomfortable and cause pressure spots that can lead to pressure sores (decubitus ulcers). Turn dad every 2-3 hours if he can't turn himself. Left side then back then right side then back.

Believe it or not, this will all work out. You'll get your groove on and be a pro in no time.

Take care "Sweetgirl74" and good luck.

I have only 1 thing to add to SueC1957 video.. While the person is on their back, pick the leg up closest to you and bend the knee completely. All you have to do to turn the person then is push from the back, and on that knee,. the person will roll with no problem. Dido on the other side. Be sure to flatten leg out before rolling from the opposite direction.