Download from here: http://moz.com/tools/seo-toolbar. ...
Then click on “Add” when you see the prompt.
To launch it you can either click on the little “M” icon in the top right of your browser or use the hotkey: CTRL + Shift + Alt + M.
to check if a link is no-follow or do-follow, you will have to check the page code. In case you have to check if the link a website provides through signatures is no-follow or do-follow, check some other similar links through the page code again.
You can check if a link is dofollow or nofollow in its html code, if there is written in html code of link that it is nofollow then it is a nofollow link otherwise it will be a dofollow link. You can also use an addon in chrome or firefox browser to highlight the nofollow and dofollow back links.
No follow link are that links those are with relation attribute with no follow text and Do follow are those links those don't have any recreational attribute.