First of all, inform yourself. We strongly recommend learning at least the basics of how Bitcoin works to use it securely. More info
Then, you need to choose a wallet to store and send Bitcoin.
And finally it's time to get Bitcoin. You can choose to buy Bitcoin or accept it as a payment for goods and services.
Popular ways of buying Bitcoin:
- Bitcoin Exchanges
- Bitcoin ATMs
- P2p directories
To buy bitcoins from your local flat currency please see this fantastic list of exchanges.