Keyless entry

Hi everyone, Hope someone can help me out. I have a 2001 alero that has power locks but no factory keyless entry system installed. I bought an after market keyless entry system and want to try and install it myself. The problem I have is I have no clue where to start. I don't know where to locate the unit itself and it came with a couple of relays and I don't know what to do with them. Any advise or help anyone can give would be greatly appreciated. Thanks.