How do you change a diaper without getting messy?

Your baby should be on its back.

Place a clean diaper underneath the soilded one then take the dirty diaper off SLOWLY and fold it down, wiping with the clean side as you go, so the poop is between the front and back sides of the diaper and away from you.

If you have a boy, put a wet wipe over his genital area

Then take your wet wipe and wipe front to back. In other Words, start at the anus and wipe away. Make sure you cover your fingers completely with the wipe.