connecting 2 basestations

i just had a friend give me an airport extreme base station, i have an old airport express and want to connect the 2 to hopefully get better coverage in my place as well as use airtunes for music in a different room. can this be done? does anyone know how to do it? the extreme is working fine..but i cant seem to get the other other one work.

running a ibook G4 with lepoard.