use items with special actions

I have searched the manual , but I have not read any instructions on how to use an item, like an amulet with charges or the Sandthief's Ring. the items placed in their proper spot on the "paper doll" do not seem to have a quick number to activate, and they do not go into a quick spot (Wrong Item Type message).
So how do I get the special effect of these items working?
Thanks, Gorris75