do everything the same but dont make a loading folder. just put the loading image right in the folder with the rest of the stuff.
mapname_map_base.tga and mapname_map_slots.tga are for the random and fixed position map preview
to make a nice one open mapname_mm.tga in a photoshop program like gimp, then add these dots & numbers for the spawns: 
http://www.filefront.com/17475812/RelicSpawns.tgacheck mapname.info and make sure it looks something like this:
HeaderInfo =  
{
   scenarioname = "Name (6)",
   scenariodescription = "Description",
   maxplayers = 6,
   date = "25-9-2010 20:54",
   scenarioabbrname = "",
   savedname = "",
   version = 2004,
   mapsize =  
   {
      608,
      416,
   },
   music = "SOUND/MUSIC/GENERICMISSIONMUSIC.BSC",
   scenariotype = 2,
   modname = "RelicCoH",
}
red part is important!!!
for weather options use this tutorial:
http://www.gamereplays.org/community/index.php?showtopic=298638in the comment section u can find all the codes and assigned weather descriptions to use with custom atmosphere settings