3: gluing the inlay: if your pocket is perfectly cut with no gaps then you just insert your inlay and glue it in with either superglue or epoxy. the truth is that there will be gaps and they arent pretty so here's what you do. get some sawdust that matches the wood being inlaid (you just made some while you were pocketing) and either mix it with epoxy to create a slurry that fills the gaps when you glue in the inlay or fill the gaps with sawdust and wick in extra thin superglue which will solidify the dust into a solid. the more you can clean up now the easier it will be later. use a shop paper towel (the blue kind) wetted w/ a little bit of alcohol to clean up the epoxy. I think (don't quote me on this) that a shop towel wetted w/ a little acetone will will wipe up the superglue but you have to be very fast.
4: leveling the inlay: once the glue is dry you will have to level the inlay so that it is flush with the surface. This is generally done by sanding though sometimes a razor blade is used to chip away dried glue.
guitars are very expensive to practice on, so are exotic hardwoods and shell. get yourself some scrap wood and practice inlaying on that until you are confident enough to work on a instrument. also, have fun, inaly is one of those things where the concept is simple and the application is endlessly amazing. Cheers,