Google: Follow No Follow links. Does not pass on credit to an outbound link. Are you sure this is technically correct? Yahoo: Doesn’t Follow NoFollow links. Are you sure this is technically correct? -Collee
When we use the term "nofollow", it represents a link with the nofollow attribute inserted. <a href="http://www.mysite.com/" rel="nofollow"> This is important in SEO as it stops the Google Page Rank transfer. Therefore keeping the page rank local. When we use the term "DoFollow", this represents a site that allows links with no "nofollow" in them. For a forum, blog, wiki, etc. to use the nofollow tag, it is the sign that there is no SEO value to that site. So when we say it's a nofollow site, we are saying that it has no SEO value or SEO worthless. What we have also found is that sites that are nofollow, start getting less traffic because the SEOer stops using them. Remember, getting a link is what this is all about.
its simple avoid rel="nofollow" tomake sure you are not wasting time on useless link, All SE ignore nofollow links
You can read my post on Robots Meta Tags to know more about them, though really there is nothing overly complicated about them and I don't you will be needing them, though having knowledge of how to use them is always good.
It would be useful to read this post with a list of DoFollow links: Build More Quality Backlinks To Your Blog