As with any ftp client, you will need to set up the ftp details.
Forget the
http:// bit.
In the browser, your site would be
www.yoursite.com
The ftp details are probably
ftp.yoursite.com
You will need your user id and passowrd that you created when you set up the hosting.
Again, these are details you would have needed for ws_ftp anyway.
Note that some host providers require you to put your files in a subdirectory. Ones I have used are www and htdocs. These details are provided by your web hosters.