How do I move BitCoin from cold storage into CoinBase?
To move your safely stored bitcoin into the unsafely dangerous online wallet, you first import it into a normal wallet, and then send it from there to the online wallet.
So you would get a secure computer os (such as
Tails) boot a pc with that, import your cold wallet there using perhaps an
updated Electrum (IMO you should skip step 2 to leave no traces), and then make a transaction to the online wallet.
Then just pray Coinbase doesn't disappear tomorrow, because, its not in your hands anymore....
Whatever you do, don't use windows or your regular leisure computer for handling serious money things. You have been warned.