Test cases on web application

I am new comer in QA testing.
How to write test cases on various application, is there any format for writing test cases, If yes pls send me that
If i want to write test cases on any web application how can i write it
What in basic difference between test plan & test planning?

I suggest you to read already posted threads here.You will learn a lot, and your all questions have been answered already in these threads.Just explore them, before posting any new thread.