Is this what u needed j.b??

http://community.bistudio.com/wiki/Mission_Editor

Marker mode is primarily used to place visual map icons and zones on the mission map. Markers are only visible while the mission editor is in marker mode, but can still be manipulated while in other modes. To do so, hover the mouse cursor over a marker's position to display it's name. The second use of markers is to define a possible starting position for any number of objects. To do this, create a group link between the marker and the object. The object will begin the mission at any one of the markers it is grouped with or at it's original position, chosen at random. This offers another way to create some randomness in a mission, with more precise control compared to using the object's Placement radius option. Note that any marker used in this way will still be drawn on the mission map (although setting the axis sizes to 0 can be used to hide a marker). Markers can not be attached to objects. To create a map marker, double left click in empty space.

Also

For creating terrain
http://community.bistudio.com/wiki/ArmA_2_Terrain_Tutorial