This tutorial will show you how to create an FTP user with Cpanel. Once you have a FTP user you can allow that user to upload files to a specific directory that you want.
1) Locate the add FTP User icon in your control panel. The icon is called “FTP Accounts”.
2) Choose a username, password, and the directory you want the FTP user to have access to. You can leave the directory blank to give the user access to the main directory.
After you create your FTP user you can use any FTP client to connect to your account. The host address would be whatever your domain is listed after the @ symbol (where you chose your username). The username and password would be what you just created.