Most engines an directories will have a blank serach box for you to enter your keywords. When you search for Africa, you'll find only Africa. Including or excluding words. Search for phrases. Try a little Boolean.
Most search engines recognise Boolean operators.
AND finds only documents containing all the words or phrases. OR finds documents containing at least one of them. NOT excludes a specific word and NEAR find documents containing both words within 10 words of each other. Ask the engine for help. If you're having trouble getting the results you want look for a help page.