Odd Picture

My niece showed me some thins to do with my camera and I tried one of them out. The blades on these windmills were spinning like mad but they look totally still in this picture! But OryK, when I tried to do the opposite effect all I got was bright white! What was I supposed to do to prevent this??? I'm so inept! But thanks, I'll keep fiddling with it! We are with daughters three and four now and so glad to be here! I backblipped YESTERDAY