I'm sure if they gave you ftp access, you don't have to specify your paricular project in the address, just simply ftp://sourceforge.net
as your username and password will determine your home directory where also your homepage/project is viewable from, etc. And I'm sure they also use the default port of 21. You might want to either supply some error messages as anything could be wrong and we're not psychic.
Also it might be a good idea to contact sourceforge if your not able to connect, etc.