Connect the watch to the computer, add your watch to Garmin Express making sure you enter login and password to the same account that you use on your Garmin Connect app.
What tmk2 says is correct. After you have done what s/he says, Garmin Express should initially display a list of the devices you have registered. If you do not see your Venu Sq, it might first make sense to check that your computer is seeing it – look at all the devices in "This PC" if you're using Windows.
If your Venu Sq is being seen correctly by your computer but is still not appearing in Garmin Express, choose "Add a Device" in Garmin Express.
