Locate and click 'Appendices/Attachments' contained in the left-hand menu:

Then click 'Check Out' in the top righthand corner.  This will prevent other users from making edits while you are working.

Once you have checked out the workspace, your edit options will appear in the bottom left corner of the work area: 

For this area you have the option of adding almost any type of document possible.  Most programs will only add attachment files.

After clicking 'Add Attachment,' an upload screen will populate.  Click 'Upload from Computer':

The upload from computer function allows for traditional attachment additions by clicking '+ Add Files' or the user can choose to simply drag and drop the files into the cloud icon.  Once all files are moved into the cloud area, click 'Start Upload.'  After all files have successfully uploaded, the status bar will show 100% complete.  Click 'Upload and Close.'

Then click 'Save and Return.'

You will be directed to back to Check-In/Check-Out screen.  Click 'Check-In' in the upper right corner.

If you have made a change to an area you will then be directed to a comment screen:

For initial entries, you can click 'Return to Work Area.'  However, if you are making edits to your Assessment Plan, it is a good idea to leave a comment briefly describing the change(s) made.  Once complete, click 'Submit Comment.'  This lets your colleagues who work in the area after you what you did and why.