Slow down the amount of times you call the sprite command by use of a variable, and the wait command... hmm... but the wait command isn't very useable in games, for the most part, but maybe this will help some:
`load images
load image "dark01.bmp",1
load image "flower01.bmp",2
load image "fire.bmp",3
`set initial x, and sprite the image once
x=1
sprite 1, 0, 0, x
`main loop
do
`only change the sprite image if change=15
if change=15
`inc the image number, and make sure its not above 3
inc x
if x=4 then x=1
`sprite it
sprite 1,0,0,x
change=0
else
wait 200
inc change
endif
loop
something