well...to use a fog all you have to do is open up your game, go to data base and click on the tab saying tilesets and there should be a drop down menu and next to it, it says fog, just click a fog to use from the drop down menu, now what it does is that when ever you are in that map the fog you use will move over your character and map so if you picked to used sand storm as a fog and you used that map then it would look that a sand storm is occuring when your in that map and autotiles are when you have a patch of water and put it on your map, but when you join it together with te same tile of water then the the two pieces of water would join up...sorry if this is a bit confusing but its hard to put it in simpler words right now.