After you've logged into your Knaken account, you'll see the dashboard. Here you will see a list of your crypto (you may need to scroll down a little to see this). Next to bitcoin is a button that says 'buy'. After you click this button a window will open. Here you can fill in the amount you need to pay. After you've bought the bitcoins, you can send them. On the dashboard next to bitcoin it says 'send'. When you click 'send' a window will open. In this window you can fill in the amount and the wallet address.