It's sad but true, we're not redyand probably never will be.

Meh. It's a simplification of what went wrong. I'm not a Communist myself (I'm a mutualist/pluralist anarchist willing to settle for radically democratic socialism), but I'll speak up in defense of the comrades.

The problem with Communist societies (stateless, democratic societies wherein the maxim 'from each according to their ability, to each according to their need') is in the method of revolution. You can go the Autonomist/Left-Communist/Council Communist/Anarcho-Communist route and have a mass worker's insurrection creating a communist society. Such societies tend to be short-lived, not because of internal instability, but because of an inability to defend themselves from external attack. However, internally, they tend to work out more or less as Marx wanted (though admittedly, we've yet to see how long this lasts on a large scale, because the large-scale ones tend to collapse from external invasion. However, many small-scale examples have been successful, and the Zapatistas have been around for over a decade now and indicate that the model can work well for at least that much time).

To solve the problem of mass rebellions being hard to orchestrate and of worker's republics (such as the Paris Commune, Anarchist Spain, Anarchist Ukraine, etc) falling, the International and the communists (after kicking the Anarchists out) settled on the idea of an intermediate socialist state to guide the revolution to Communism and defend it from reactionaries (capitalist states, aristocracy, nationalists, etc). Hence the 'dictatorship of the proletariat'. Note that the proletariat is a class, so a dictatorship of the proletariat is literally supposed to be the rule of the working class, through democratic worker's councils, or soviets.

The Bolsheviks in Russia took this a bit further thought up the idea of the Vanguard party, which basically states that a party of dedicated revolutionaries needs to lead the soviets to communism. This vanguard party was successful in warding off the many, many enemies of the revolution (including the White Army and invasion from Germany, Poland, the WWI Allies, Japan, and, later, the Nazis), but also took control from the soviet councils, ended democracy, instituted political repression, committed crimes against humanity, and killed off their political opponents, such as the Mensheviks and Anarchists. This all created a society that was not a federation of soviets, as originally intended, but a military dictatorship of the Party, which became a new class in itself. The means of production were not controlled by the workers, but by the hierarchy of the state.

And that catch-22 is the problem with communism.

So...

... we need to kill everyone?

This is very true.
We wouldn't need governments or supervisors or laws, either, because people would actually share and be nice to each other for a change.

Then why don't we stop greed?

Communism was always great idea but the rulling people always screwed it up..same reason why democracy isnt as it should..like in my country,freedom of speech and crap riiight

Aye, that is true. It could also be because we're xenophobic as well, liking to live in isolation.

in a global way its possible
you have to show the poeple that fairness is better than egoism and the wish to get more money then a poor country

those supercapitalists have so much money that the y dont know what to do with they earn money just to have it and thats shit thats why i hate em and thats why im communist

sry im german and my english suxx^^

It's officially human nature to covet things, hence capitalism and why it and the big corporations still thrive. We're greedy bastards I tell you! hah