Basically, once you create the joint structure and placed it accordingly to your mesh size/position, what you need to do is to manually skin your mesh on the skeletal hierarchy.
So select your mesh/meshes, select your joints and then go to Skin > smooth bind
I guess that the easy way is to follow this tutorial which explain the step-by-step procedure to skin your custom mesh 
Anyway, next time google it, it takes 2 seconds to search what you’re looking for
