I'm starting off with a SharePoint development, and created a Site Definition containing, well, nothing. My plan was to create a sharepoint site using that definition and go from there, however, I couldn't figure out to
The 1st thing you need to understand are the diferences between Site Templates and Site definitions (quick one here http://www.dhirendrayadav.com/2010/09/site-template-vs-site-definition.html also click the link to Wilson's blog for more). You also need to know that in 2010 at least, it is recomanded to avoid them if you can (e.g. what is a configuration, site collection portal vs. sub-site only, want multilingual sites, etc.), but rather rely on the very flexible and powerful model of features/solutions and stappling concepts (for automatic activation of dependent features).
Then, if you still want to go that way you would need to read and understand the xml files part of any site definition (e.g. onet.xml) because via Visual Studio 2010 that's what you get. You could also start with an existing one, closer to what you are targetting, see more here http://msdn.microsoft.com/en-us/library/gg512104.aspx or http://msdn.microsoft.com/en-us/library/gg276356.aspx
That should get you started.