never used coinbase. ok, so u have bitcoin on coinbase. first i recommend you follow these steps:
1) download and install Electrum wallet (
https://electrum.org/#home)
2) setup a bitcoin wallet in Electrum (search google for instructions)
3) WITHDRAW ALL your BTC from exchange to electrum wallet (see on payment page it says DO NOT send bitcoin from an exchange) (YOU CAN FIND YOU PERSONAL BTC AADDRESS INSIDE ELECTRUM BY CLICK "RECEIVE" TAB.
4) BTC arrive in Electrum wallet. Then click on send, enter amount and BTC address shown on payment page (DO NOT EXCEED COUNTDOWN LIMIT ON PAYM,ENT PAGE!)
5) take your time. dont rush this. one wrong mistake and your money is gone...