Hi:) ,
I want to know what is the procedure of admission in American universities for foreign students??

You will need to contact the admissions dept of the specific school you wish to go to. They will have forms for you to fill out, they will need your past schools to send them documentation of your education. Most have adviors who will help you with your education visa and the such.

But in general you will just need to decide on what schools you would like to try and get into, and then apply to them

You definitely need to contact the schools you are interested in. Most accredited (and many non-accredited!) universities and colleges have a place on their website for "international applications".

There are so many factors... previous school experience, visa, financial documentation, standard tests, and if you come from a country whose primary language is not English, you may have to take a test to provide proof that you speak English well enough to understand upper level classes.

I worked in admissions at a large US University for 4 years... you really HAVE to contact the schools you are interested in, as each school has its own requirements for international students.

Yes please contact the school, I worked for a major university in GA and they had special departments just for international students to help them.
Even special classes on English if that was needed to help them up to college level english.

So some are a lot better than other in services they will provide, and what they require for admittance

1) Approach school
2) Fill necessary forms & produce documents
3) Take up TOFEL & GRE Exams (since I assume you are from India).
4) Submit those scores.
5) Get a letter from the school stating you can study there
6) Take that letter to th embassy to get a student visa (need to show sufficient funds here. You must show that you have enough money for at least the 1st semester).