Ah, you put another question in your post regarding what kind of wire to use. Any wire that has two conductors would work. The original wire on your speakers is probably pretty thin, so you don't need anything real thick. You could use speaker wire if you have some around, an old power cord from a lamp or other device, or outdoor electrical cable.
Connecting them together can be easy. You could twist together the old braided cable and the new extension cable (one conductor at a time, of course) and then isolate each conductor with tape. Electrical tape (the black stuff) is best, but I've used regular desk tape without any issues.
EDIT: I swear that Phil is my twin or something.
