Reversing order of displayed category

I just got my site up and running yesterday and now I’m seeing the need for a few “tweaks”. The biggest one is the order of display of categories, in particular chronological order instead of the default reverse chronological order. I understand that in a normal blog the most recent post should be at the top. But when my viewers want to “ride along” on a trip I took three years ago, they want to be in the opposite order, oldest first. At least, that’s what my “beta tester” (wife) told me, and I trust her opinion.

So ultimately the question is this: do I have control over the order in which a category is displayed? I’m using the Sinatra theme, but the site has only been “live” for a day, so now would be the time to change, if that’s necessary.

The page I need help with: [log in to see the link]