You may have a broad topic idea when you walk into class today - and it may be as broad as
'first generation college students'
and that's ok. Choosing a topic is part of the research process. You're coming up with an IDEA which you then do some SEARCHing around and then you REFORMULATE your idea based upon what you have learned. You may go through this cycle a few times in different resources before you settle in on a topic you want to write about.
If you've ever used Wikipedia, and you know you have!, you already know how helpful background sources are. You can use them to look up broader topics you're interested in to discover narrower aspects you can research and what people are concerned about and researching. Look for key terms you can use to help find sources for your annotated bibliography.
You can also use background sources to understand terms or concepts that are new to you or methodologies you're not familiar with.