Where you want to add Nofollow Attribute code ? you are talking to set Nofollow Attribute in some useless links of your site or any thing Else ? please explain in details so you'll get Proper Answers. Eric
Nofollow can potentially increase traffic to your website through visibility, which means that since people will see your link then there is a chance that they will click it and in return you get a visitor to your site. A Nofollow link will not help your SEO, or google pagerank. On the other hand a Dofollow link may increase your pagerank and can possibly improve your SEO, as well as send some extra traffic to your site. Building nofollow links to your site can never hurt, but building the wrong dofollow links to your site can hurt you if you are not careful. Good Luck!
It's the opposite actually. If you use Do-Follow, you will start getting much more comments (assuming you're talking about a blog) and people will start listing your site in do-follow lists. However, some people argue that making all the comments on your blog do-follow will affect your SERPs, so you have to make up you mind on what is more important to you.
Both Attribute codes are gives you Traffic..... But Nofollow is not counted in Google back links.........