How to get a 20 day visitor visa ?

[rawheat]

I am travelling to mexico for presenting a paper at International AIDS Conference in 1st week of August . I would like to travel around US on my return journey for 20 days . Could you please guide me on it ?

[Murali]

You have apply for a USA visa separately.
read here
http://www.path2usa.com/immigration/visitorvisa/visitor_visa.htm

The process is same whether it is for 20 days Or more..