To add a document to the library navigate to “Document  Management” through the “Asset Library” link on the Header Bar.

You will be presented with the following screen:

 

Select the category that you would like the document to reside under and right click the category.  The following context menu will appear:

 

 

Select “Add File” from the menu and the right hand frame of the browser will be populated with a new “File Details” property page as below:

 

Enter the “Title” and a short “Description” of the document.   Then click on Browse and select the file that you wish to upload to the Content Management System repository.   Once selected click “Save Details” and the document will be uploaded and the left hand tree menu will be refreshed to contain the new item.