can not upload plugin

hello,

i am trying to add a forum to my blog . this is the plugin
for the forum http://www.fahlstad.se/wp-plugins/wp-forum
I used a ftp this one to be exact
http://tutorial.ftpplanet.com/Pro/connect.asp
to upload to wp – content / plugins and i got this error wp-forum.zip: Permission denied even though i am connected to the server. please can someone tell me what iv done wrong.

ps: is it something to do with the data base as im not logged into data base.

many thanx in advanced