How to connect a wireless internet to...

Hello,

can someone tell me if it's possible to connect a wireless modem to a wireless router? I have the Time Warner Cable Sierra Wireless hotspot, but I want to make it faster, so I though maybe a wireless router would help, but I don't know how to do it. Where I live at there are lots of trees and don't get much signal. I will appreciated so much if someone could help me.

Thanks in advance.