How can I create an Open Green Map?

Only registered Green Mapmakers can create a map at OGM at the present time. Get details at GreenMap.org/join. It's not free and you need to have some experience with sustainability. Once you have received the official welcome email, you can login at OpenGreenMap.org and click FAQ on the upper menu and follow the instructions under How to Make a Map. You can keep your map private until its ready.