Select wallet from the side panel, then scan or paste your LN address. 
Discussion
For some reason I was not able to put address on that Wallet tab. Address won’t paste or read scan. I went to profile>edit>Lighting Tips and paste LN address. Seems it worked.
Probably has something to do with Apple blocking the app because of their 30% kick back. Still works on Amethyst 👍🏽