So, I'm obviously not a very experienced mob maker, so ill just get to the point. after I made a custom mob, I had no idea where to put it, how to make sound, how to make an egg for it etc. would anyone be able to walk me through the process of adding it to my game?
I'm afraid there is quite a bit more to making a minecraft mob than animating it. The behavior, drop table, spawn egg items, interaction events etc all need to be built from scratch (or largely copied from existing mobs, but it still requires code).
Entities are NOT the most basic thing to work with in any version of minecraft, and I would not bother trying to learn it for just this purpose. Instead, learning an application that generates the code for you like MCreator may be a better option.
In the future, do mention the version of Minecraft you are working with, as interface standards have shifted significantly between versions :)