You can get a Tourist visa in Nepal upon arrival at the Tribhuvan International Airport, Kathmandu. You have to provide your passport and two passport-size photos to fill up the visa form, and certain fees will be charged accordingly. Outside Nepal, you can obtain a Nepalese visa at the nearest Nepal Embassy. However, the visa conditions vary to citizens of different countries. You can refer to the information regarding the Tourist visa at the official website of the Department of Immigration at http://www.nepalimmigration.gov.np/page/tourist-visa. All the tourists must enter Nepal as per the procedures mentioned at the website.