Using 2 routers to increase range??

Preety newbie

I have 2 routers (siemens and utstarcom) with me. My primary router setup is in siemens. But i am not able to get a full coverage in my entire house. So i was thinking how to increase the range by using the utstarcom router which is lying spare with me.

I think bridging or routing can solve the problem. But i dont know if i i m correct and how to do the same??