I heard that building backlinks is not enough one should promote all the backlinks. Please do give your thoughts and feedback if i'm doing it correctly. Is submitting all my backlink URL to Digg, stumbleupon, other social bookmarking sites is link promotion. Is this the correct way of promoting my backlinks? or if anyone can give me additional suggestions or guidance on link promotion it'd be of great help for me?
Thanks

you are doing is correct but don't forget one thing, add a blog or article section and update the content in that section it shows that your website is regularly updating and providing fresh content to visitors. But avoid adding duplicate content to your website.