its ok bro 

Heroes for newbies are, from the top of my head: Dazzle, Warlock, Crystal Maiden, Lich, Lion, Lina, Twin-Head

If you are completely noob you should get one of those, go to a lane with an agility or strenght hero and babysit them. That means, protect them from the enemies, stop enemies from farming and help your friendly carry-hero to farm.

Get wards, put them up at the runes, or in places where enemies can get at you from.

Here is a good ward-guide.

Depending on the situation you might want to get a variety of things, what ability does your team need? Do you need some AoE-heal, then get a Meka. Does the enemy have a hero that is utterly horrible, get a guinsoo and turn him into a sheep. Expensive item though, if you let your friendly carry farm you probably wont be able to afford it early on.

Do not talk back to people whining at you, it will only make it worse. Pretend they are being constructive and try to learn from what they are actually upset about. Usually there is a reason you've pissed someone off by being a noob, it is ok though. Just learn from the experience, try and avoid making the same mistake. Sometimes people will whine on you even when you didnt do anything wrong, those people are dicks, you should ignore them completely.

There is a minimap, look at it often, is someone missing from a lane? Who is missing, is he coming to your lane? Perhaps you should back a little just to be sure. Also, is there an enemy who constantly pushes his lane so far that you could go in from the forest and stab him in the back? Try and organise some ganking-efforts to get the enemies to die. Excellent pasttime for after you planted those wards.

If you want to become a good player, trying to get good at one aspect of the game first is probably wisest. Id suggest supporting, it is a hard art to master, but once you do, everyone will love you. Also, if you know how to support well you can observe what the carries are doing and learn from that. Also, a bad support still supports and does good for the team. A bad carry-player is always going to be utterly useless.

Considering that there are 100 heroes or so in DotA, you will not know what all of them can do until until you spent at least 100 hours in the game or so. DotA is a hard game to get into, but it is a lot of fun once you do.

Beginners Guide Source