I can't get a clear picture of what you are trying to ask. I suppose you are asking how to find high pr social bookmarking sites or how to get back link in a high pr social bookmarking site. If you want to find the sites, just search high pr social bookmarking. You may find some list of sites which have been already shared in the internet. Some of the sites i can recommend are delicious, stumbleupon, newsvine, diigo, slashdot, scoop.it, reddit and folkd. If you want to know how to submit your link, try this. Every site will have submit news or add your links, submit your story option. You have to add the links you want to bookmark. Then give appropriate titles, description and tags. That's all you want to do for bookmarking. Initially bookmark the homepage and then go for the sub pages. Try to create unique contents for the bookmarks.
How to link those sites? What are you talking about? Get a backlink? Or link them each other (like you have a backlink in one of them and link the other one to the 1st bookmarking site)? Next time, be more specific about your idea.......