I can see I'm a bit late, so you probably have the problem resolved. But for next time, here is my guide on how to change a shitty diaper:
1. Put a towel or baby blanket on the area you will be changing the diaper, usually a bed or the floor.
2. Place the wet wipes next to the baby and open them so they are ready to be grabbed.
3. Lay the baby on his/her back on the towel or blanket.
4. Unfasten the diaper on both sides.
5. Now this is the tricky part. Simultaneously lift the baby's legs slightly, elevating the butt, as you open the front of the diaper and with the inside front of the diaper which is clean, you wipe downward, wiping as much shit as you can while sliding the inside front of the diaper down the shitty area. Raise the baby's bottom slightly in the air, as you pass the front of the diaper down undeneath the butt, so that the external side of the front of the diaper will now be underneath the baby's bottom. It's important to wipe as much shit up as you can in this step.
6. Set the baby's bottom back down on top of the external side of the front of the diaper.
7. Grab one wipe at a time and proceed to wipe up all the shit. Use as many wipes as necessary. Place the used wipes in a pile, being careful not to get shit on anything.
8. When the baby's underside is clean, remove the soiled diaper, and place all of the soiled wet wipes into the top-center of it. Then wrap the diaper up into a ball, with the soiled wet wipes inside, and fasten it with the velcro-like straps.
9. Grab a clean diaper. Unwrap/open it. The side with the wide straps goes on the bottom.
10. If the baby has a rash or inflammation, apply ointment, if available.
11. Lift up the baby's butt by the leggs.
12. Place the correct side of the diaper under the baby's butt. Make sure that the front and back side are correctly proportioned so that the diaper will fasten comfortably and securely.
13. Set the baby's bottom back down on the diaper.
14. Place the front side of the diaper onto the baby's front area and fasten the side straps.
Almost forgot, if there is a woman in the house, she should be the one to change the diapers.
That's it.