tetherxp.inf for Windows XP

[BERN-ie5]

A friend gave me his old office computer. It has Windows XP in it, but no way to connect to my home WiFi network. My HDTV, & PS3 connect no problem wirelessly. So apparently I need the computer to have this file/program called "tetherxp.inf" installed in it. So what i've done is download the program from the web using my phone. Its now sitting in my phone & I dont know how to transfer the program to the computer ~ I am computer illiterate, so when i plug the phone to the computer clicking on USB mass storage ~ the computer sees/reckognises the phone ~ but i dont know how to transfer the file from the phone into the computer *?