1. Add the text that will be linked as a button to the copy.
2. Ensure you can see the Formats dropdown. If you can, click the Toggle Toolbar button
3. Highlight the text that will become the button text and select a button design in the Formats dropdown. I would recommend using either of the first two options first. (Double Carat Link or Standard Button)
4. Lastly, link the text to the URL and click in another section of the editor to see the button style.
Finished button