wireless internet

I have a client calling me with a problem.
She bought a new laptop from us. with Hp wirelss card in that. She also bought a new wireless Router from us. she have SpeedStream 4200 modem from TELstra Boradband. The Linksys wireless router she bought from us is physically connected to a desktop where internet is accessed. but she is not able to get internet on the LAPtop. Can any one please tell me how we can set this up. thanks heaps for any one who is reading this.