From the App Menu, hover over "Resources Pro" and click on "App Settings"

Choose "+ Create Resource"

Enter a title and a description for your resource. Upload a photo file for the resource thumbnail, and upload the resource file.

Choose categories for your resource. Note: Uncategorized resources will not appear on your website. 

You can add content to your page by clicking the "Options" button at the top right.

Resources Pro will allow you to upload as many files as you like on a single site.

For more information on Resources Pro within the Marketplace