Almost everyone need a visa except nationals from Burundi, Congo, Rwanda and Zimbabwe who can visit for up to 90 days.
Nationas from Kenya, Mauritius and Tanzania can visit for up to 7 days visa free.
If there is no Congo embassy in you country you may be able to apply for a visa on arrival by contacting the Direction Générale de Migration by email. We have no idea how to get the email address.
Visas start at US$100
Visas are available if you want to visit Virunga National Park for US$105
Democratic Congo visa requirements
Virunga National Park