Once you're logged into the Control Panel, you can upload files by selecting your server and then Files > FTP File Access
Once you're on the next page you will be prompted for your password, enter the password that was provided to you in your Server Activation Confirmation email
You will then be presented with your servers file access, here you can upload, download, delete, zip, unzip and more!
Select multiple files/folders to complete actions against all of them, such as delete or adding to a .zip archive