Crap, uh, yeah, damn I can't remember it's been so long... It works a lot like a 1st/2nd Ed Matrix run, you progress through a series of LAN nodes, I just can't quite remember how it works. I think you need to use a LAN Scan utility to see what's there, then a LAN Probe (?) to make your way around. Unless there's no security and you can just go there by clicking on the node.
Try going onto the Introversion forums, somebody on there probably has a LAN FAQ up.