Hello @iowafemale - The Samsung support page has some pretty easy looking step by step instructions for installing the EKG app on your phone here:
https://www.samsung.com/us/support/answer/ANS00087702/. The site is kind of kludgy with ads popping up and having to X them out. The website has some pictures to go along with the steps but here are the steps.
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Install the Samsung Health Monitor app
First, make sure to install the Samsung Health Monitor app on both your watch and phone. Once you download the app on your phone, it should automatically install on the watch as well.

Note: The Samsung Health Monitor app requires a Galaxy Watch Active2 or Watch3 on the most recent software, paired with a Galaxy phone running Android 7 (Nougat) or later.
1. Navigate to and open the Galaxy Store on the connected phone.
2. Search for and select Samsung Health Monitor, and then tap Install.
3. When it's installed, open the app and follow the on-screen instructions to set it up.
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Pair your watch and phone
If you haven't done so already, you will need to pair your watch and phone together in order to use the ECG feature in the Samsung Health Monitor app. You can connect your devices via the Galaxy Wearable app.
1. First, swipe down from the top of your phone’s screen to open Quick settings, and then tap the Bluetooth icon to enable Bluetooth.
2. Next, navigate to and open the Galaxy Wearable app on your phone, and then tap Get started.
3. Select your watch model from the list of devices. Wait for your watch to pair or tap Scan for nearby devices to search for it.
4. Follow the on-screen instructions to finish pairing your watch and phone.
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Update the Galaxy Wearable app
To ensure your watch can sync correctly to the Galaxy Wearable app on your phone, you will need to make sure the app has been updated. The latest software is also required to use the ECG feature. You can update the Galaxy Wearable app from the Galaxy Store or Play Store.
1. Navigate to and open the Galaxy Store on your phone, and then tap Menu (the three horizontal lines).
2. Tap Updates to check for available updates, or tap My Apps to see all of your apps.
3. Then, tap the Update icon next to Galaxy Wearable.
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Set up the Samsung Health Monitor app
When the Samsung Health Monitor app has been downloaded, your phone and watch have been paired, and the Galaxy Wearable app has been updated, you can finally start setting up the ECG feature.
1. Open the Samsung Health Monitor app on the connected phone, and then tap Continue.
(Galaxy Watch3 discovered and Continue option displayed on a Galaxy phone)
2. Fill out the necessary information, and then tap Finish.
3. If prompted, tap Set up lock screen, and then create a lock screen for your phone.)
4. Next, tap Swipe up to start.
5. When your watch is discovered on the phone, tap Get started. If your phone is having trouble discovering your watch, open the Samsung Health Monitor app on your watch. Allow the permissions, and then tap Open phone app. Your phone should then discover the watch.
(Get started option displayed on a Galaxy phone)
6. Follow the on-screen prompts and review the information shown.
7. Select the wrist where you’ll wear the watch (left or right), and then tap Done.
(Left option selected with Done displayed on a Galaxy phone)
8. On the watch, read the information, and then tap OK. Your watch will then ask you to perform an ECG reading. You can do it now, or do it at a later time.