How to replace AT&T provided software with original software?

[catch2mee]

I have AT&T Samsung Galaxy S3. I would like to remove AT&T provided android OS and install standard (non service provider version) or international version of android OS. I would like to know what all are the requirements and how to do it. I am very new to android. Any link to the process or video would be great help.

 

[Rukbat]

First learn to create ROMs. That should take a few months of daily study. Still interested? Probably not.

 

[catch2mee]

Yes, still interested in it and would like to get top of it. How and Where can I start? or should I use the existing ROMs available for free?