How do I go about setting up travel from Moscow to MSP airport USA? Is there an agency called Agen Travel?

If I want a friend to visit USA for two to three months what do I have to do? Temp visa and how do I apply for one?

Contact the embassy or consulate for the USA in your country.
If there is non, or you cannot find it, contact any other USA embassy and ask them where you need to go.
The embassies all have visa info on their sites.
How to apply, what documents to bring or send and the cost.

Next you go to a travel agent, or check on-line and look for the price of a ticket.
Make sure when you buy a ticket that you can return it if you do not get your visa.
(You may need to buy an insurance for that.)

It seems there is a travel agency called Agen Travel, but I have no experience with them, I just found them on internet.
http://www.lastminute.com/site/find/World/Europe/France/Aquitaine/Agen/Agen--travel.html

And here is a site that has info on what visa you need for what travel:
http://www.delta.com/planning_reservations/plan_flight/international_travel_information/visa_passport_information/index.jsp

I have written this answer as if for the person in Russia, if you want to organize from the USA, you can use the same websites, or you can phone or e-mail immigration services in the USA, they can send you on. (Their website might have all the info you need.)