Re: So confused with GRASS
If you are new in the GIS topic and you want to strt using GRASS, I suggest you to start with the document "Grass in a Nusthell":
Grass does not include any maps, because the maps depends on the location where you want to solve a particular problem. So, when you start working in a specific problem, you will have to ask for the maps to someone else, depending on your needs, but there are several resources on the web.
If you want to start working with grass just for learning, you can download the Spearfish sample dataset from this page:
which also contains information that can be useful for you.
I hope this can point you in the direction that you want.