How do I check the amount of backlinks to my site and how do I know which sites are linking to my site ?
HI google webmaster tool or there are different plug ins for different browsers are available , or one can use online tools like backlink watch for backlink checking .
Well, the best way is to check the backlinks with the of Google tool bar, it will show you best results of back links that you are having in Google.com, Google follows contextual link building that's why you will less back links in Google as compared to Yahoo, MSN or any other search engine ....
BLC is ridiculous - it appears it only shows the links from the sites it had crawled, and there are not that many
I want to just know about that if I have placed a link on nofollow site then google can consider it while counting my PR and indexing my website?
It will be equal to a link from a non-PR page (which is still a good link, but it won't contribute to your site PR)
ahrefs.com has a pretty cool graph view of your backlinks. It is a little bit on the conservative side, but pretty nice. You only get so many submissions daily, so use them sparingly!
Thanks you everyone for your answers. I have just signed up for Google Webmaster Tools and it has answered my 2 questions.
You can use Seo Profiler or in case if you are a SEOMoz member, you can check the amount of links through the Open Site explorer