In the FileZilla folder, start the FileZille Server Interface program.
On the Edit menu at the top, click on Users.
It's probably a good idea to remove all the current users (in the upper right box). Then use the Add button to add a new user. (You can probably leave the Group drop down alone.)
Then, make sure the new user is selected, and in the middle there are options for "Enable Account" (probably already selected) and Password (which you need to check, then enter a password - you do not want to have any way in to your server without a password).
Then, in the left box, click on Shared Folders. Click on Add, and you should get an Explorer-like windows to select your home directory.
If you need to add more directories, say so, because it seems to be a little more complicated after the first one.