A friend of mine gave me a 4 port entrega hub. Unfortunately, she didn't have the instruction book -- a really necessity for folks like me. I can't figure out how to hook it up. I get that there's a power plug in that powers the hub, and 4 ports, but there's another plug in on the hub shaped like a square with two corners cut off. I can't find any plug on the back of my computer that looks like that. Can someone point me in the right direction, please? Thanks so much.