To receive Crystals or start chatting in Surf, you need to share your wallet address with another person.
You can find your wallet address using any of three methods:
Click the Surf icon in the upper left corner of the main app screen to go to Settings, and then to Safety Protection → Address and keys.
Click the Receive button or downwards arrow in the lower right corner of the main app screen.
After the address is displayed on the screen, click it to copy or scan its QR-code.