øTo add a new marker with information, first navigate the map to find the location you wish to mark (you can move the map by dragging it, you can zoom in and out, etc.). Put the information about that area into the "Text to add:" textbox, then click on "Add marker", and click on the map where you want the marker to go.
This is so that this map remains uncluttered and useful for those needing the information.
If you can't see the marker you just added, reload this page.
I want to thank Greg Stoll for putting this together really quickly for me. You can check out his site at www.gregstoll.com.