Thanks for answering me so promptly, amandafayes:
It's at the top of the page, near the right-hand corner. It's a small panel that contains a list of options, one of which asks you whether you wish to follow the person whose work you're perusing. Inside that panel is an option that says "friend" and a box already-- automatically checked.
I simply leave the box checked when my intention is to add the user as a friend.
Good luck. There are more bells and whistles here than at FLICKR. Sometimes I feel like I'm in a big room and a glee club is singing (!).
Good drawing, painting and/ or photographing today,
Your friend,
Norman