You do NOT need to complete all of the items; only complete the items for which you are submitting changes/updates/corrections.
To begin, you'll need to find your site's unique 'VTA Site ID.' See the image below which shows where to find it on the interactive web map located at:
Search for your site in the box on the upper right and press return. The site ID will appear listed with the site on the list to the right of the map. Alternatively, you can use the filters on the left to find your site and/or hover over points on the map.