How can I change each to renew page of 'up part' photo in WordPress?

My WordPress page is http://aslihanoztunc.wordpress.com
But how can I put more photo to up part? I want, when you clicked 'refresh the page' button, than photo change.

I don't actually know what u mean,
but if you want to change your header image you can use header image slider or rotator wordpress plugins
e.g
http://wordpress.org/extend/plugins/header-image-slider/
http://wordpress.org/extend/plugins/cimy-header-image-rotator/
here tutorial : http://byronyasgur.wordpress.com/2011/07/07/simple-wordpress-header-image-rotation-slideshow-fader/
if you use free domain service of wordpress, you can't customize your blog