Any wireless router should work just remember that that ibook only speaks 802.11b so the router must be set to speak b as well. Dual mode (b/g) should be fine. The airport icon is in the upper right of the menu bar and clicking on it should summon a drop down menu showing available networks to join.
PB G4 15" 1.2ghz - Pismo G3 400 mhz - iBook G3 500 "Jukebox"
"SawSmurf" G4 500 - Quicksilver G4 Dual 1ghz modding...