your hatchling is in for a very tough time right now. tail loss is going to be extremely stressful on its' young system. to be completely honest, if your hatchling is very young, there is a realistic chance that something like this may prove fatal.
1)seperate the gecko into its own enclosure. you want to be able to monitor this one easily and you don't want it being stressed by other geckos.
2) use a papertowel substrate while the gecko is healing. this will help keep the wound clean while it heals.
3) give it *plenty* of hide spaces. you want to make life as stress-free as possible for it.
i don't know how humid it is where you live, but you really need to mist at least once daily. you can use a coco fiber substrate, to help retain some humidity.
good luck.