To frame my problem, please use this site for reference: Ethan Beyer | Prints.
Essentially I want to do exactly what this user is trying to do: http://wordpress.org/support/topic/change-the_excerpt-to-the_content
The difference is that I am using the Boumatic Theme (child of Thematic), in which there is no "loop.php" and I've never coded with PHP before.
When a visitor (or I) choose to look at a page devoted to a category, I want every post to be displayed in its entirety, not just an excerpt. I understand what is happening in that other forum post, denoting that the excerpts are still shown when something is searched for - but for the archives, I'd love the whole post to be present.
Can anyone tell me how to change this (which template files do I need to edit, etc...) or at the very least point me in the right direction?
Thank you very, very much.