Steps:
1. Zoom all the way out in mapmaker
2. Press the print scrn key
3. Open paint and press ctrl+v
4. Save the image
5. Upload your image to a server.
6. Put the image into your topic with the [IMAGE] tag
When you make the screeny, use www.photobucket.com - it hosts pictures, and it also has a feature where it will tag the image for you, just incase you dont know how. You dont neccisarily have to put it in IMG tags - you can just make a link to go to the picture directly.
Yeah, yeah, so I decided to stay noob-friendly.. for a bit, anyway.
I'd give you the link to the shading tutorial, but you've got the colors down alright. You just need to round out the shapes a bit, and it'd be much better.
Instead of having just simple triangles, add something on the corners to round it out. Using more advanced shapes makes for a much better map. 'sides, the pointy corners are usually glitchy and stuff, so try to avoid sharp edges.
If you need ideas as to how to round out poly's look at the tutorials in the help section. They're VERY helpful and get the point across. The general idea is to use very small poly's to create a rounded edge. Its hard to explain the shapes and stuff, so just take a look.
Shading is the general coloring of vertices and poly's to give the map a more realistic feel and look to it. You seem to have it down as Reaper explained, so dont worry about it.