Changing order of posts (newest posts last, oldest first)

Help! I installed the plug-in Comic Press to start an on-line comic strip, and I need to reverse the order of posts, so that the newest posts (the most recent comic strips) appear at the BOTTOM, and not at the top. I’m a total newb here. A friend familiar with WP told me the easiest way to do this is to edit the core files. ComicPress theme overwrites a lot of the standard wordpress template hierarchy, so he doesn’t know which file he needs to make the change to. I need to figure out what template file controls the output of the comics on the homepage.