First of all, congratulations for succesfully fixing your first flat and finishing the ride.

You may want to practice a few tube changes just to be more familiar with the process before you have to do it on the roadside again. But then again, you managed to get it done and you'll get more practice eventually.

I don't like to rely on CO2 for roadside repairs. I prefer to carry either a full size frame pump or a Road Morph pump on my road bikes. (Mini pumps are for masochists). I'm even thinking of starting to carry a Mtn Morph in my camelback on the mountain bike. Unlike CO2, pumps keep working no matter how many mistakes you make.