mahsood first off welcome to the Avaya forum. Pretty much anything on the Avaya side you can find here. Several ways of doing that is to do a search at the top of the page for whatever you are looking for. Odds are its been covered in another thread. Also be sure to look at the FAQ section. A lot of our members have taken time to post things that will help others in there.
This one
faq690-6418
Would be a good place to start. It covers all the basics. Should you ever have anything specific you need help with feel free to post. We have a lot of great Avaya tech's here.
When is the last time you helped someone, just because you were able to?
For the best response to a question, read faq690-6594