0) Make a Click event handler for the Button
1) In the Click even handler grab the username from the textbox
2) Make sure the username is valid (e.g. it's not an empty string)
3) Create the url using the username.
4) Use
WebBrowser.Navigate[
^]
I hope this helps you, as it's not really clear to me what exactly your problem is, except that you cannot get the
WebBrowser
to navigate to your url, solved i the 4th step