A basic start:

Download SQL Express 2012 SP1 with Advanced Tools. Install, and experiment with it.

A cheap start:

Buy SQL Developer edition, install and experiment.

An expensive start:

Become an MSDN subscriber and download whatever you need for development.

Mid-level version:

Download two or more different versions (one of which is the latest), and install both (one as a named instance) - now you can play with a more enterprise environment.

Find examples. Try to accomplish them in different ways. Compare the results.

P.S. Focus on backups and restores first - that way, you can have a good starting state, try something, fail, and then get back to your starting state for another try. I like Ola Hallengren's procedures, which I modify slightly. http://ola.hallengren.com/[/url]