If you are using MetaMask to store token from a token sale or from a purchase you made on an exchange, you can manage your tokens basically the same as you do your Ether, with some slight differences. MetaMask doesn't have a feature to send your tokens currently - you can only view them within the browser extension. However it's simple to send tokens through MyEtherWallet using MetaMask.
However, if you try to send tokens without having any Ether in your account you will be told you have insufficient funds. This means you do not have enough Ether in your account to cover the cost of gas. Each transaction (including token and contract transactions) require gas and that gas is paid in Ether. You can think of this like a transaction fee.
You can remedy this by sending 0.01 ETH to that account in order to be able to make the transaction.
A standard Ether transfer TX will be 21000 gas & a gas price of 8 GWEI.
With tokens, the amount of gas is typically 200000 gas, so the total TX fee increases to 0.001 ETH - 0.002 ETH.