If there is no wireless then you need to go wired. On the back of your wireless router I guess you'll find at least 2 possibly 4 may be more UTP ports. In a way they look like slightly larger USB ports. I guess your router is connected to another box - your modem (although sometimes there are 2 boxes in one) - this will have the type of UTP (network cable) connection I'm talking about.

See the picture in this link (sorry the writing is all in Dutch - ignore that look at the picture!)

http://www.pcwereld.be/forum/algemeen/netwerk-internet-en-telefonie/5584-laptop-naar-pc

You need to use these types of network wires from your laptop (there should be one UTP port on that) to the router / black box in your friend's house (which does not have wireless)