That's going to be hard though. The slave traders used to mix up Africans from different countries and tribes (so they couldn't communicate with each other, which could lead to a revolt) so looking up your geanology from your two parents you will likely find that come from more than one African country.
It could also be from when slave families would get broken apart when some of them were sold off, and the women could have possibly forced to have sex with other slaves from another slaveowner (to breed more slaves).
In Henry Gate's roots program the black celebrities who took DNA tests got various results. I think Chris Tucker had Ghana and Angola. There was one woman who came from FOUR different african countries