To verify your identity:
Tap the Home icon in the menu bar
Tap the Settings cog icon in the top right of the screen

Tap on Identity Verification and complete the steps
Some tips to ensure the identity verification goes smoothly:
Take a clear picture of your identity document, where every single detail is readable
Take the photos somewhere brightly lit
Turn flash off to avoid glare on your documents
Make sure the details on your SeamPay profile match the details on your legal document
Do not take a picture of a picture