Adding and editting points is easy and free. First there are a few hoops to jump through:

1. Create an account: click here.
2. Then wait until the site moderators ok the account.
3. Then sign in with your password and click 2D Map in the top menu.
4. You wll see the same 2D Google Maps-based map, but now with an extra link "Add New Marker".
5. Zoom and pan the map to where you want a new marker.
6. Click on "Add New Marker" and then click on the map.
7. Fill in the Name of the site and whatever other information you want to add. You could for example add a picture.