U.S Visa for 1 week

Hi All

I need some suggestions and help regarding the procedure to the U.S visa for 1 week for an event.

One of my friend got opportunity to attend an event in U.S which is going to happen coming October and he got the letter from his company and he is going to represent his company and he got the tickets for the event. But we are not sure what visa we need apply and what are the procedures involved in this procedure to get the visa and how long normally they will give the visa?

His company asked him to get the details to proceed further.

Please advice

Thanks