Photogallery Align problem

hello ,
I was working on photogallery tutorial.Everything is working quite well for now except one small thing.The gallery loads the photos without any problems but all the photos are aligned to left and I have to make them centered.I think I should do it with as but I didnt know where to put which code in the as of the gallery.If you guys can tell me where to put a code and make the images loaded by xml centered I’ll be really really happy :-/