You'll need to first create a new folder on your hard drive where all users can access the files. Then create 2 subfolders (this is the way I do it) named "Download" and "Upload" whereas the "upload" directory is where users can upload files. Start by creating a user account (You'll need one if you only want authorized people to access your files)
1) Go to the "setup" menu and select "User accounts." Right click in the "user accounts" space and click add. You can edit the password of the new user if necessary. Now right click in the "access rights" space and click add. This will allow you to set the virtual directory; which is the directory where the users will be put in when the login. (Set the directory to where you will be storing the files). After you have done that there are a list of options to the right. Select the directory and then click on Read, Write and Append (You don't want to fiddle with the Delete option). And then finally under the "directories" menu click on Make, List and +Subdirs. Do that now, and it's the first thing you should probably do.