How do i fix this?

i am very very new to avatar creation aka i started like 20 hrs ago. i got everything right, put everything where i needed to, connected everything.. but somehow the shirt i have stays in a t-pose and doesnt move with the breast/cheat. can someone please explain why this is happening?

Where did the clothes come from, and how are they attached to the avatar? looks like the clothes aren’t attached to the same bones that make up the body.

So they’re either different bones, or an entirely separate armature (term for bone set?)

Basically tell us (collectively) about this:

looks like no weight paint on the clothes? make sure that the weight paint is on the right bone as well. other then that, no clue.