Seperate copies, for now I just want to connect my laptop to my little bro's. We dont have a good internet connection where we are right now.

This is in short what you need to do:

1. Hook up your Laptops in a LAN (either a cross-link cable, using a switch/hub or a WLAN adhoc network)
2. Disable firewalls (because these usually block most games even in LAN)
3. Start Sins
4. Player 1 Selects Multiplayer->LAN->Create Game, selects a map and clicks "Create"
5. Player 2 Selects Mutliplayer->LAN->Join Game, clicks on Refresh and the game should appear in the list. If it does, select it and click "Join". If not, check if:
a) are you running the same version of Sins?
are firewalls and other "port-protectors" switched off?
c) Player 2 may try to enter the IP of player 1 directly in the IP-adress field and click "Join" (IP Address can be retrieved in Windows using "Start->Execute->cmd" then type "ipconfig" and hit return)

If you are having trouble with point 1) tell me which approach you are using and I'll try to help.

Agreed. If you are additionally hooked into the internet then add an exception rule to the firewall settings. If your Laptops are not in the internet at all, turn it off.