General Support: I need some info on customizing

Hi, I have implemented plogger on my next version of my site design, still is notfully available, have a lot of work to do andi'm still loading the gallery.

But some changes would be nice to the design I need.

Well I would like to display the collections and gallery's thumbs and caption with a different style. I want these to show in columns with the text description on the right. So to do this i think I need to use on the display of collections and galleries with different ul.slides and slides li styles. My problem is not knowing where to apply this new css styles on the code. I think i need to make changes only on gallery.php but do not know what lines of code control the display of galleries and collections. Anyone can help?