You can use these steps:

1. Start the console: ./webchaind console or (webchaind.exe for windows)
2. Get your balance (on console): web3.fromWei(webchain.getBalance(webchain.coinbase), "ether")
3. Start mining (on console): miner.start()
4. Get your balance again to confirm you are mining: web3.fromWei(webchain.getBalance(webchain.coinbase), "ether")