Documents can be associated to a single feature or multiple features in the map.
Select the Open Module tool .
Right click on an asset (or select multiple assets and right click) in the map. Select "Associate New Document" and select an asset or one of the "All asset" choices.
After selecting the desired option the Select Document to Associate window will appear. Browse to the document or enter in a website or hyperlink. The document description must be filled out.
Once you have entered in the appropriate information, click Attach.