How to Weld A Part/Model to Player's Character [?]

i dont understand a thing and i dont hav script, plis halp me TwT

You could use RigEdit plugin to weld the model to the torso.

So more in depth, take what model/part you want, position it how you'd like and use the RigEdit plugin to weld the model to the torso.

I don't know much about this, sorry.