documents for parents GC

[resham]

I have been scheduled for oath in May.
After getting my citizenship, I wish to apply GC for my parents.
What all documents are needed by my parents so I can begin gathering it.
Another ques, does my parents need to be in US while applying?
I would highly appreciate your suggestions.

Thanks,
R

 

[pongap]

Look at http://www.immihelp.com/greencard/familybasedimmigration/index.html