Adding a sky in your map:
1) Decompile Town.mrs + Yourmap.mrs
2) Copy the files Town_obj_sky_daylight.elu (9kb) & Town_obj_sky_daylight.elu (32kb) (two different files) to Yourmap folder
3) Open Town.rs.xml and copy <OBJECTLIST>
<OBJECT name="Town_obj_sky_daylight.elu">
</OBJECT>
4) Open Yourmap.rs.xml and paste that code between </MATERIALLIST> and <DUMMYLIST>
5) Compile Yourmap
6) Test and have fun .