How do you get to Malawi?

You can fly to Malawi. It has a number of airports and you can fly to them from other countries. Depending on where you are, you can get flights to one of those countries and then fly to Malawi.
If you are traveling from the United States, a routing through Addis Ababa, Ethiopia is usually the most direct. Ethiopian Airlines operates out of New York and maybe D.C. Another option is South African Airlines, but then you are flying all the way down to Johannesburg and back up two to three hours to Malawi. The airport with the most traffic is Kamuzu Airport in Lilongwe, Malawi's capital, but many airlines fly to Blantyre as well.

If you are already in Africa, you will still likely wish to fly as your ground option is minibus or coach with very long stops at any international borders.