help for tiles (for my first game)

hello,
I need your help for my first game

I open a window :
WindowOpen(1,"COSMOS",0,0,320,200,5)
CanvasOpen(1,320,200,0,0,320,200,0)

I can of course load lot of images to declare sprites/tiles like this :
pacman=1
LoadImage(pacman, "pacman.png")
etc.....


But i will have lot of PNG images ! I prefer to load a full (hidden) image (320x200) which contain all the sprites/tiles (16x16)
and put these tiles into variables by cutting


Can you give me the procdure ?
Thank you