Map Editing

Hey guys , i just started map editing and i'm thinking of making a prehistoric map. I've uploaded a background image that looks like this: http://australianmuseum.net.au/uploads/images/7177/g012%20late%20cretaceous%20map_bi.jpg .
Here is my problem , whenever i start a game to test it , my land and naval units can move anywhere on the map , even though there are land marked areas and water marked areas. How can i do so i can limit the units in different areas ? And yes , i tried "Limit to Contries" option at every unit , but that's useless. I believe i need to set the area where for example land units cannot go , but naval units can.

I hope you're not using that image. It's way too small.

Could you please screenshot your map in the editor?

Nope , i'm not using that one , i resized it. Here's a screenshot: http://imgur.com/w5xnSM1