Hello and welcome,.
Now to install a theme you need to send it to your phone via blutooth,usb cable or be e-mail if you have set an account up on your handset.
Then the best thing to do is to save it to mmc/sd card.
Hope this helps
Please search next time as your querie has been answered before,see here
http://www.4urmobilephone.com/forum/viewtopic.php?t=675