With your iPhone you can do this as follows:
1. Open the Tomorrow app on your iPhone
2. Go to Profile > Card and click on the "Apple Pay" option button and follow the instructions

or:
1. Open the Wallet app on your iPhone
2. Tap on "Add" or on the plus symbol (+) and follow the instructions

And here are the necessary steps for your Apple Watch:
1. Open the Apple Watch app on your iPhone
2. Click on Wallet & Apple Pay and select ‘Add credit or debit card’
3. Enter the 3 digit CVV number on the reverse side of the Tomorrow card connected to your Apple account