mobile wifi help

I am trying to gain access to internet via my wifi. All my computer stuff is on the opposite side of the house and up the stairs. For some reason I cannot connect to wifi from my phone HTC sensation. How does one increase the distance from which they receive wifi without going out and buying an antenna. I know the answer is in one of these forums and I am about an hour or so into looking and nothing.

 

You cant. you will need to buy a more powerful wireless router