If you followed the “Add Locations” instructions (found here) for a community member, and entered your locations within the Community itself, you have already shared your products by doing so.
If you have added and shared locations with a community, but now need to share locations with another business, click on the Community name you wish to share with, first click on Locations under Connect Setup in the left navigation bar:
Next, select the "My Locations" tab at the top:
Next, select the communities you wish to share by checking the box next to their names:
Once you have selected the locations you want to share, click the "share" action button (shaped like an arrow):
You will then see a popup that requires you to select the businesses you want to share with:
Once selected, click the OK button. You will then be notified that you have shared your locations successfully: