Nepal being a surrounded by lands country in Southeast Asia, any one get into Nepal by flight or land through India or China. You can get the Nepal entry visa on your arrival in Kathmandu airport or now days you can get online visa services also .
Entry points between Nepal and India
Entry points between Nepal and Tibet China
Nepal has only one International airport .it is called Thribhuwan airport in Kathmandu. There are many International flights that connect with Kathmandu Nepal.