You can fly to Kinshasa from Abidjan (Ivory Coast), Bujumbura (Burundi), Douala (Cameroon), Johannesburg (South Africa), Lagos (Nigeria), Luanda (Angola), Libreville (Gabon) and Nairobi (Kenya). Although planes are now flying from Kinshasa to the east of The Dem. Rep of Congo for the first time in years, the east is more easily accessed via Kigali in Rwanda. Most airlines have offices at Kinshasa's N'djili Airport. Alternatively, book through travel agents. Carriers include Kenya Airways and SN Brussels Airlines.
You can travel to Brazzaville in the Republic of Congo via a daily ferry across the Congo River. The cost is USD 25.00 and the ferry runs 08:00 - 16:00 (until noon on Sundays).
Flying is largely the only way to get around the vast territory that is the Democratic Republic. However, airplanes are old and badly maintained and due to inadequate safety records, most of the airlines have been banned from operating in Europe.
Train travel is possible - though not recommended -from Kinshasa to Matadi, Lumbumbashi to Ilebo and Kalemie via Kabalo and Kisangani.
You can also travel by road to Matadi, and then into Angola. From Lubumbashi you can get a train to Johannesburg or Dar Es Salaam.
If you have enough time and aren't fussy about privacy you can travel by barge along the Congo River from Kinshasa to Kisangani. This is the real highway of Central Africa and a wonderful way to see the country. However, there is no fixed timetable for the departure of barges and they often break down or get stuck on sandbanks along the way.