How is Upgradation Process takes place?

Hi Experts,

I sincerely thankful to all who are providing solutions here. I have recently moved to Up-gradation environment from 4.6c to 6.00 ECC. But I need your help before i start up with pace in this assignment. Please give me an Idea at what point

Up-gradation takes place and how it starts and where it ends.I would really appreciate If anyone can help me How to start this in step-wise method.

Thanks in Advance,

Kanna Palle.