are you from india, if yes from where??
that is something that you can say in a PM not as answer to the thread just to fill number of threads mate. people trying to help and no need to spam threads just to get the number.
imagine everyone saying in a thread: hi mate how are you? i'm fine thanx, what you do for living........
of course i don't intend to insult you and give you behavior lessons, but keeping clear threads so people can find info easier is the right way.
OP, i guess you have searched here but have not found anything to help you.
but you opened the thread at the section which you would find the answer

.
Tier 1 and Tier 2 are categories of links at the called "Link building Pyramid". you can find very much info here about it and there are tons of good threads which explain exactly what it is and how it can be implemented.
I would like to write a thread about it, but there are already some threads who explain it, so i will not write a new one.
but can make you a short explanation about what it is.
Tier 3 blogs can (Example 100 blogs) can link to ----> tier 2 blogs (Example 20 blogs) which will be linking ------> Tier 1 Blogs (Example 5 Blogs) which will be linking ------> your main site (Money site). in that way T3 passes juice to T2 etc etc.
i am pretty sure that you will find a lot of nice threads which explains exactly how to do it and what is the more effective way of tier link building.
good luck on your research.
Leobar.