how to autologin to a website that uses authentication form

Hi I am trying to auto login to a website that uses authentication form through my windows app. I need it to auto login once the navigate button is pressed. On this website there is an xml feed and I need to grab a value from that feed and bring it into my widows app. and assign it to a string.

Any thoughts on how I could accomplish this?
if anybody has anything that could help me out I would appreciate it very much

thanks