lol, i couldnt stop laughing when i saw your title "how to play dota".

ok, here r some simple steps:
1. hold ALT & press F4, do it twice.
2. then leave your house, go to the nearest CC & see how ppl play it.
3. next buy a copy of WC3 & frozen throne CD each before heading home.
4. while back home, install the game & DL aota all stars latest map.
5. start playing.
6. DL good replay & study.

i guess that asnwer your question