Do you mean:
(a) "intra-africa" (african country to/from african country)
(b) "extra africa" (african country to/from countries ousyide africa)
or
(c) both (a) and (b)
Are you specifically looking for air cargo movements or trade by mode of transport (so air and sea/surface)
are you looking for weight & value
Depending upon what it is you are looking for I can point you to a source, but be aware that this sort of data can be very expensive
I'll look again to-morrow
Cheers