Das Kapital is far, far, far too complex for a beginner.
If I'd want to get someone interested in communism, I definitely would recommend the Manifesto; while it isn't detailed, or anything, it explains a little bit the goals of communists.
But most likely, I'd direct them to www.cpusa.com I became more interested in communism after reading their FAQ a while back; it's simple to understand, especially since most "beginners" don't know much about politics, economics, etc.
Now since man is naturally inclined to avoid pain - and since some labor is pain in itself - it follows that men will resort to plunder whenever plunder is easier than work. History shows this quite clearly. And under these conditions, neither religion nor morality can stop it.
When, then, does plunder stop? It stops when it becomes more painful and more dangerous than labor.
It is evident, then, that the proper purpose of law is to use the power of its collective force to stop this fatal tendency to plunder instead of to work. All the measures of the law should protect collective ownership and punish plunder. - Brederic Fastiat