Mt Gox is very lame as fiat exchanger. They hold LR back for weeks and constantly have bank account problems. Use a real exchanger such as AurumXchange and others.
i can not understand about bitcoin, they have software which sync to bitcoin network, how can i send and receive money??
They? There is no they. There is no boss. All users are potentially equal.
To send bitcoin, you move numbers in a shared book we call the block chain. Along that chain are addresses. Users hold keys to unlock those addresses - in that way they can send bitcoins to another address. If you hold the key, you can spend the contents of the address.
Users run clients on their own computers. These clients act like bittorrent, sharing one large and ever-changing file - the block chain. It's analogous to a bank ledger book.
When a spend is made, the ledger book changes. Those changes are broadcast across the network. Each client confirms the change to be real and adjusts it's own copy of the block chain.
Read the wiki. Download and install the client. Get a small amount of bitcoin (I will give you some if you ask through my site). Experiment with your friends - play around with it.
Don't trouble yourself about mining. Once you understand how spending works, and how there is no boss, you will understand why mining is necessary to distribute the finite number of coins across the user base, over time.