How do you work a joomla file…. i cant find the right file to edit??? whenever i open up a page it opens up the web browser then a download link appears and now im confused?? can anyone help

Photo gallery for Joomla where members can upload images?

I started a website with joomla and I want to add a photo gallery to each different page (it »s a camaro website and each page is a different generation). What could I use that enables the members who sign up for my website to be able to upload their own pictures to the gallery?