Having feedback problems!!!!

O.k. so I'm not the most computer savy member here, I'm trying to leave feedback for the great deals I've made here and I'm probably not leaving the correct thread address. The page address does not come up on the sellers feedback. If I find the tread from which the transaction was made, where do I find the address?

Right click in the blue area of the thread and go to "properties".

Copy and paste.

Thanks.