First, here is how to find your resource library:
1. Select Content from the navbar
2. Under the Content header you will see Resource Library (the third option), select it
There are two ways to add a resource to your resource library:
1. Click the blue area and select the file from your computer
2. Drag the PDF from your computer into the blue area
Note: You will have the option to upload PDFs directly into a resource content block that you add to your page.