First select the asset you would like to send, and press the "Send" button.
You will then see a popup where you can either paste an address to send to, select a contact in your address book, or scan a QR address/request. After entering the recipient's address and any "Tag" or "Memo" that may be required by the recipient, press the "Continue" button.
Next enter an amount to send, by either typing in the asset quantity or estimated value inputs, or alternatively pressing the "ALL" button to send your full balance of the asset, and press "Continue".
Finally, on the confirmation screen make sure to check that all the details are correct and press "Send". If your wallet is not currently unlocked you will be asked to enter the password or PIN, and on unlocking the wallet with the correct password or PIN the transaction will be broadcast on the network.