If you have torn your tire, you will need to patch the tear or else the tube will pop out of it like entrails. The best patch is a glue-on tire boot, but it’s unlikely you will be carrying one, and torn tires should not be used past the ride on which you tore them. Good substitutes are energy bar wrappers, race number plates or, if necessary, dollar bills held in place with a touch of duct tape.
Clean the inside of the tire off in the area you are placing the patch, and hold it in place with tape until the tube is inflated, to stop the patch from moving around during the repair. Try to cover a much larger area than the tear.
Check the tire sidewall frequently during the remainder of your ride. The tube produces a lot of friction against the tire, which can wear through your tire boot quite quickly.
Tip: If you have a big tear in the tire, you can always try sewing it up. About the only thing strong enough for this purpose is (believe it or not) dental floss. You may need pliers to force a needle through the tire sidewall, and you will definitely need a patch over the stitching to protect the tube, but this may be sufficient to see you home. Mmm. Minty Fresh.