Socketing

Ok so it has been a long time since i have played and for the life of me and even after searching i have come up empty. Ho do i add a socket to a item? I have all sorts of gems, runes, and jewels and for the life of me i cant remember how to add them to the items i have. Just picked up an armor piece with a socket or two on it and a weapon that says 1-3 sockets on it and is orange and is an eth. Cant seem to figure out how to add these things to them. I have the cube and im completely lost on how to use that also. I know its a noob question but even my searches have come up empty, im at a loss so any help would be greatly appreciated. Thanks in advance!

 

If you're using the maphack that came with the patch, hit the "Insert" key to unlock sockets. It's a toggle to prevent adding something to a socketed item by mistake.
All cube questions can be answered here: The Arreat Summit - Items: The Horadric Cube