All ingredients for repair. It is an art not a science.
Lightweight sail repair tape is a must in your Hobie box. It is thin enough to make a luff repair if needed.
A sailors palm and appropriate upholstery needles and upholstry thread and a little knowledge of sewing with a high tolerance for pain and no aversion to blood (your own)
You can apply the tape and stitch in place for some repairs.
A good primer on sewing can be found at http://www.thru-hiker.com
as well as useful material knowledge.
Overall however, this is information for emergency fixes. A sail-loft does a better job. My sails underwent years of patches until I had a sail loft replace a panel and the luff and bolt ropes and batten pockets and caps. It was still good when I sold it after another 4 years of use.
Hint on the Jib if have battens- foam battens and sewn shut pockets help prevent a lot of hang up.
Have fun Todd!