How it works depends on your wallet provider, but usually there is a transfer button on your wallet page. After clicking it, put in the amount you'd like to send as well as the receiver's wallet address.
Note: bitcoin transactions are confirmed on average once every 10 minutes, and generally require 3 confirmations to be considered complete. For ether, that number is around 50 network confirmations. All transactions should be visible to both parties as soon as sent. Read more about confirmations.