I do have some art posted on my facebook page for my friends to see and I know that some of my friends have facebook pages dedicated to their art alone. I would like to ask anyone tat's ever promoted their artwork on facebook if it's effective or not.
Of course it is effective to some extent. It depends how much effort you actually put into promoting the artwork itself. I personally post my work on my main facebook page as well as my business page. We live in the modern age and social media is the way of spreading the word nowadays. Whether it be Twitter, Facebook, dA, Flickr, Red Bubble, Tumblr, Wordpress, Blogger, Instagram (shall I go on), etc....
at your level, you should be more focused on practicing your art than promoting it. once you get good, you won't have to promote it - it will promote itself.
I don't have a facebook for my art but i do post on my facebook what i am working on now. I think that facebook is a great tool for artist, i follow many artist on my facebook. Its an amazing tool to get people from all over to view your art. I would say follow some of your favorite artist and see what they do..... what their posting, how they get people to go to their site and comment/like. It may help you understand how to use facebook for your art. I do that with a lot of sites i follow very popular artist and see what their doing and whats working for them.
I've used facebook a couple of times. Usually my friends will take a peek to see what I've done, but only three or four people probably care. But hey, any bit helps.