haven't used blender in so long I'm forgetting like the most basic of basic shit.

Say I have two objects, object 1 and body 1, body being an avatar (it has an armature, etc) If I want object 1 (it's a ring) to attach to the body so when I move the finger in pose mode it will move the ring with it..how the fuck do I do it?

Right now I'm selecting object 1 (ring) then shift+selecting body 1 (the avatar body) and hitting ctrl+j to join them. Now the ring is no longer it's own object I only have the body, but when I move the finger in pose mode the ring just floats there doing nothing instead of moving with the finger. I mean I assume this means it needs to be weight painted but I've never had to weight paint when doing this simple procedure in the past so I must be doing something wrong here?