You cannot get backlink that will help you in Google for top ranking, you can get some traffic from them. If you are looking for backlinks, which will help for ranking is dofollow and not from these websites.
You can not get backlink by creating ppc ads with the social network sites because your ads only run and is removed when your money finish. But you can get backlinks from social networks by creating account with the social network and including your domain url in your profile and in any post or thread you make at the social network site and let your achor text be your site niche keyword. By so doing, your site may not rank number 1 on google search alone but you could easily grab number 1 position by pigibacking on those social network sites . Thank you!