Open Settings → Account & Security and select Set up 2FA. Scan the QR code with an authenticator app such as Google Authenticator, Microsoft Authenticator or 1Password, then confirm the current six-digit code while entering your password.
When 2FA is turned on, Organise You gives you recovery codes. Store them somewhere safe outside Organise You. Each recovery code can be used once if you cannot access your authenticator app.
You can generate a replacement set of recovery codes or turn 2FA off from the same security area. Both actions require your current password and an authenticator or recovery code.