Here are some instructions on how to sew an adult women´s sun hat. I think there are many different ways to do it, but this is just the way that I have figured out for myself. It is very windy in Wellington, so I´m aiming to not just make any old hat, but specifically one that will stay on a strong breeze (which is the purpose of the string casing etc). I´ve made a couple like this so far here and here. Even though the pattern was different, the basic sewing instructions were the same.