Would someone please tell me what the above blue tab called Bookmarks is used for or how it is used?

well you've got the answer already I only add. In bookmarks embroiderysites are posted, or sites that is interesting for embroidery.
And in Freebies are the links posted where you find a free design of a site.

That's where we use to "bookmark" other good sites for freebies or anything we embroidriers might b interested in. Not many people use it anymore since we have the freebie tab now where we r suppose to post freebies. *