Thank you all for replies.
I now have BTC in a desktop wallet and I would like to sell some. How do I get some back to the Coinbase exchange to sell?
(I'm new to this and the interfaces are a bit intimidating.)
Exchanges interfaces are varied and they have all different features that set them apart from each other, they have a tutorials on Youtube you might want to download tutorials on every exchange that you want to trade, so you can refresh yourself every time you are trading on one particular exchange, that's what I'm doing.