You need your ip address followed by the port number LW is using. From the LW search page, click where it says "Direct Connect"(lower left of the page) and it should list your ip addy and port number. That's the number you should give your friend. And you'll need thiers to browse them.
You'll both need to have your firewalls configured properly for it to work.
See this thread:
How to use Magnet Links & Direct Connect
Another good place to find your ip address is here:
http://www.whatismyip.com/