I assume that what you are saying is that you need examples of how only a few countries in Africa are doing at all well. If so, I would turn to the CIA's World Factbook.
By using this resource, you can look up facts about the economies, educational systems, and other things about various African countries. If you use the actual cia.gov link, you can click through and find out how African countries compare to others.
For example, you could find out that Benin has a GDP per capita of $1600. That means, more or less, that the country produces $1600 per year for each person that lives there. You can also see (use the link that ends bn.html) that Benin is 198th in the world in this category. If you click on the little 198 there, you get a chart of the GDP per capita of all the countries in the world. (Or copy and paste this link
Using that, you could look for all the countries in Africa. You'd see that, for example, there is only one African country in the top 50 for GDP.
You can use the Factbook to find out literacy rates, rates of infant mortality, and other things that show how well off (or not) a country is.