If you want to come to the United States, you need a visa. And if you don’t intend to come here permanently, the B2 Tourist Visa is the best option for you.
While it’s called a “tourist visa,” it also extends to other things: it can be used to enter the United States to study as well. It’s mostly given to students who are attending school full-time at a USCIS approved college. However, shorter classes can be permitted if you’re not taking it for any credit, and if the work is less than 18 hours per week.
The most common reasons people use a B2 visa, though, is to visit and look around (and sometimes visit family here, too). It is also used to come to the U.S. for medical treatment.
If you wish to apply, you can do it a few ways. You can complete an online visa application, the DS-160. You will need to include a photograph with your application. The rules for this photograph are explained here.
There will be an interview, though it is generally not required for those under the age of 13 or those over the age of 80. If you are in between those two ages, you will need an interview. This can be scheduled at the nearest U.S. embassy to where you live.
Remember that you must also have a passport valid for travel to the U.S. You may also need to state the purpose of your trip, when you plan to depart the U.S., and that you are able to properly pay for the costs of your trip.