Give these tutorials a look to get an idea of how/what you can do with Joomla. http://www.compassdesigns.net/tutorials/joomla-tutorials/

Don’t try to learn it all. Just browse thru and try a few things on your own site. Get a feel for it.

There is so many options that it can be intimidating. But reading through the tutorials can help give a better grasp of the concepts. Once you get the basics down, most of the options and features start to come into focus.