On my steam account under TF2 it says "Play Team Fortess 2 for FREE until June 13th on your Mac or PC. New to TF2? Haven't played in a while? Check out the new Training and Offline Practice Modes to polish up your skills. Don't have Steam? Get it here. About the Game" But how do I download it to play for free? It is also 50% off and only gives me the option to buy.. I want to try it out first.. How can i do that?