What are these things, i know there important but what are they? do we need to put our site url in the actual comment, or is putting it in the email section enough?
Dofollow means that google will follow the link and it will be considered a good link, and google will use it to judge the rank of your site. you can have dofollow links from the actual comment text and also from the url that you enter before you write the comment and then it attached to your username that you use. on my blog the url is dofollow and the comment area is dofollow too, but as always it helps if the link is in a similar category to you page also. Nofollow links arent used by google to affect your page rank or your websites worth!
Do follow means to pass on. If you have placed your link on do follow blogs, then it will become a good back link to your site with the same PR which the page contains. Yes you need to place you URL in space given as its link to your website.
Most dofollow blogs are strictly moderated - so if you're going to comment purely to get a backlink, make it good.
Well...for most do-follow blogs, the name links back to your URL and hence using your keyword can be used as name to get a backlink. Most but not all do-follow blogs allow HTML anchored texts inside the comments to be do-follow as well which is more efficient for SEO point of view. However, as Kerosene just said, better make your comments noteworthy to compensate for the obvious spam.
There are 2 kinds of links in this world, Do-Follow and No-Follow. Both look like a link and both when clicked on will send the user to another webpage. The difference is that a "Do" follow link "does pass" information to Google (the fact that there is a link to your page, and the Page Rank of the link will pass thru to you) a "No" follow link is just a link that sits out there but doesn't get picked up by search engines and doesn't pass any value on. So if you want to gain Page Rank on your website, increase search engine placement, and get organic traffic a Do-Follow link is way more valuable than a No-Follow link. No-Follow links can get okay too if you are getting traffic from it. If you got a No-Follow link to your site on a very popular and busy website you could get lots of targeted traffic that clicks your no-follow link and goes to your site. This is obviously valuable traffic as well, it just isn't going to help you get people to your site straight from the search engines. Make sense?
I follow the logic, infebious, but is "do-follow" equivilant to a regular link (i.e. <a href="X">Y</a>)?