To join a 'shared wallet' with another Bitcoin.com wallet user, you will need to either scan the QR invite code, or the creator of the shared wallet will have to send you an invite code.
To join a shared wallet by scanning the QR code, please follow the steps below:
Tap on "Scan" and scan the QR code with your phone camera
Your wallet should automatically take you to the "Join shared wallet" page
Enter your "username"; this will be your co-payer name
Tap on "Join Wallet"
Back up your part of the shared wallet and keep the backup phrase safe!