I love Aquaphor. It is absolutely hands-down the best product to treat diaper rash that was ever invented. My daughter came home from the hospital with terrible diaper rash. Everyone recommended a couple of other brands, but they didn't work! Her pediatrician said to use Baby Aquaphor as well as to wipe her bottom with a wet tissue instead of a wipe which can irritate a newborn's tender skin. It worked like a charm. I have been using Baby Aquaphor ever since! I don't use the tissues anymore unless she gets a very bad case of diaper rash. In most cases a day or two of Baby Aquaphor does the trick. I also use it as a preventative measure so that she won't get diaper rash as easily.
It comes in a tube or a jar. I prefer the tube because I can just squirt it onto the offending area and don't have to scoop it out with my hands. I just use the diaper to kind of squish it in the area. The rest my daughter does herself when she's moving around.
This is great stuff. Buy it for baby shower gifts!