You have to sync the watch with Garmin Connect, and if it does not work for some reason, try syncing over the USB cable to a computer with Garmin Express.
If it does not help, you can try this: Remove and Add a Device From the Garmin Connect App | Garmin Customer Support, then log a few minutes of steps and HR, and record a test activity, sync, and see whether it helped. If not, then have a look at the Troubleshooting guide for (some) data missing after syncing for more tips.
