Go through your results for flights to Kinshasa in Zaire with Netflights. The most popular airlines for this route are Brussels Airlines & Ethiopian Airlines, with Brussels Airlines claiming the top spot. Although Ethiopian Airlines usually has the best prices, it's best to double check what's available for your travel dates.
Flexible on dates? Conducting your search by month allows you to compare prices to Kinshasa throughout the year. For example, prices will almost certainly be higher around August, as this is peak season in Kinshasa. Accommodation prices will also be higher at this time of year. Flights to Kinshasa are usually cheapest in November.
Kinshasa receives two direct and indirect flights every week, but the cheapest airline is normally Ethiopian Airlines. So, if the flights to Kinshasa don't work for you, you could always try searching for flights to other airports in Zaire.
Looking at a few different departure airports will give you even more choice. See what you can find. And remember, it's best to book your flights in advance wherever possible.