business travel from sierra leone to Shenzhen

I think that probably a tough trip. The Lungi International Airport only has direct airplanes between some countries in West Africa and Fance and London.
In my opinion, if you want to go to China, you may need to take the flight to Pairs where there are direct and indirect fligts to China. You can take the direct fligts to Shanghai or the indirect flights to China via Moscow to Shanghai, and then take the Chinese domestic plane from Shanghai to Shenzhen.
This is probably a cheap way from your country to Shenzhen.