put the img tags in between these tags
[spoiler][/ spoiler] make sure that you unspace the / and spoiler so it looks like /spoiler inside of the [] brackets ok.
its should look like this [spoiler][img]c:\desktop\naruot.JPG[/img][/ spoiler] (with out the space between the / and spoiler ok)
make sure to put what you wont hidden in the spoiler button inside the spoiler tags. there you go this will work for ya.