I have just introduced a friend to this board and I can't remember how I added "Free offers and donations" to my profile. Can you tell me how she can sign up for those postings?

The easiest way is to click on your profile at the top of this page.
Look for this towards the top of the page:

You can see the list of all sections on the board and subscribe/unsubscribe here.

Click on the word "here" and then you can subscribe to whichever sections you would like to have show up :D:D:D

took me awhile to find those too