Put the 48x48 ".bmp" in elona/user/graphics named Pic_#.bmp where the number is between 2 and 16. Or put the 48x96 ".bmp" background .bmp there with a number from 17 to 32. For Omake variants the numbers in filename are starting from 661 onwards instead, so in the end full path will be "elona_folder/user/graphics/chara_661.bmp".