Hiya eta,
An Easy way to start off a map is to use the Bmp2Map program that is avaible to download from AH terrians. All yaneed to do is is find the template file and draw what you want your map to look like in a grey scale image where white is higher and black is lower. flat Black (0,0,0) is water. then base layout is a simple task that is just place a fliad correctly and move on to the next field!
Hope that help you.
Regards,
Skull12