First of all, setup the WebUI on your PC (see the utorrent website for instructions on how to do this).
After that, you will need to enter your username and password under the settings section (click on the title to get the main menu).
under hostname you will need to enter the computer's IP address (unless you have winbind working or are using a hosts file). To get the IP address type 'ipconfig' into a command prompt on the server and look for a line labelled 'IPv4 Address'.
Hope that's clear enough