to change the stage selection screen pictures and icons in sm4shexplorer go to data/ui/replace/stage, extract the stage folder. these files you extracted are all of the stage icons
the dlc stages are in a data/ui/append/stage.
Stage_10- i dont know qq (maybe smash tour)
Stage_11-bigger picture on the left of sss (when you are hovering over a stage)
Stage_12-stage icon during replays
Stage_13- small SSS icon on left of select screen
Stage_30 the stage icon during classic mode (the hexagon the figures are on)
Stagel_10- logo of the stage
Stagen_10- stage name
The most important files are the ones in Stage_13 and Stage_11 because those are the only ones seen in a normal smash battle
sorry i wrote his really quickly, if you have any questions just reply to this post or pm me on gamebanana (01-Green) thats the best place to contact me for mods.