As a disclaimer to anyone;
DotA is one of the most complicated games you will ever encounter. It has a ridiculously high learning curve, and mastering it can take
years. The community is very hostile towards new players, and at lower levels filled with self-entitled idiots who will blame you for a loss when they spent 30 minutes feeding with a hard carry. It will wrestle you down and break your spirit on a daily basis. People will regularly yell at you over their microphone in foreign languages where all you can translate is one thing--anger. You will encounter some of the worst sportsmanship, and some of the worst people imaginable.
BUT
It is one of the best games I have ever played. Even with the complexity, the requirement to learn hundreds of hero and item combinations, and the hostile community, it is one of the most rewarding games I have ever played. A game well played in DotA is one of the most exciting experiences in gaming
because the game is so complicated and difficult. Nothing is more exciting than a perfectly executed gank where you land a triple kill, or a Pudge hook thrown into the fog of war at an unsuspecting enemy, or a team fight where your team counters everything the opponents have to throw at them. DotA walks a fine line between exhilarating and enfuriating.
If you win this ticket and have little or no experience with MOBA's, prepare for the worst, and I hope you have a knowledgable friend to help you, but
do not quit after a few games. Play a couple games a week, and I guarantee once you get past the growing pains, you will love this game. There is a built in system that allows you to play against Bots of varying skill levels, and they are planning to add some kind of tutorial mode as soon as they can. There is a "Learn" tab that will show you all the information about items and heroes. There are also hundreds and even thousands of sites with various guides and video guides on how to play the game, each hero, and basic to advanced game mechanics. USE THEM ALL.
If you need help I will personally assist you because I am so passionate about DotA. I've gotten home from work at 7:30am some days and immediately jumped on Twitch to watch Chinese tournaments for an hour or two before I go to bed, or squeezed in a game or two before or after work.
This is the first guide any potential DotA player should read:
Welcome To DotA, You Suck.
Good Luck all.