file manager and user permissions

[totamus]

I just acquired a website that is on a dedicared server running plesk - and I have no plesk experience. The site is running, but I need to maintain it. I need to use the file manager, but every time I try to use it, I am denied permission. I cannot make directories, move or copy.

I am logged in using the main account for the server.

From my research, I believe I have a user permission issue - but how to fix it is making my cpanel brain hurt.

Can anyone give a complete plesk newbie guidence?