The look of plogger stems from the themes. Plogger is set to the default theme once you install it. To integrate it onto your site you will use your stylesheets ontop of the plogger style sheets. Your webpage will look just like yours but on the photo/plogger section your website would use it header footer and nav bar but have plogger central on the bag. That is where you need to start to get plogger intergrated on your site.
Also, silba, the link you provided is an .html page, not a .php page. You will most likely have to rename it photos.php and it should work then. The rest of the site can remain as is (with HTML tags, etc.), but the PHP code has to have a .php extension for your server to load it right.
My site is www.hooliganscomics.com and i want to integrate my gallery in to the page so i don't loose the look of the site but I'm having no luck. i hope i am putting this in the right place, sorry if not. what ever info is needed just say the word, i can post any code or screen shots or what ever you ask. thanks in advance.