I think the easiest way is to make sure you have everything you need nearby (wipes, ointment if they have a diaper rash, etc). I put the clean diaper underneath the dirty diaper before opening in case the baby isn't finished yet. Then open the diaper (and be careful if you have a boy as he might shoot you when he feels the air lol) and hold the baby's legs up and wipe him/her clean and fold the dirty wipe in the dirty diaper. Then just take away the dirty one and close the clean one.
*Also, I usually keep an extra diaper at hand in case baby decides to let loose again after I take away the dirty one.How do I change a diaper?
Look on you tube- they'll be a demo on there which will talk you through the steps.
You wife will think your a pro by the time she gets home!How do I change a diaper?
Here's the link :] The same goes for toddlers.
http://www.youtube.com/watch?v=aMsPZ1SPSHow do I change a diaper?
you take the diaper off, set it to the side. hold their ankles so their butt doesnt touch the floor. wipe their butt an their junk. use enough baby wipes til its all gone and clean. put baby powder on them if you want to keep them dry and so they dont get a rash. if they arlready have a rash, put desiton on it, or let them get some air. goodluck