There are a number of tutorials online, the details vary but they are all pretty much the same in essence. For example-

e6a21cd105e303edf05f81e5728baa2e.jpg

Just Google "how to wear a great kilt" or "how to wear a feileadh mòr".

You will require approximately 9 yards of single width fabric cut in half & stitched together to make a piece of cloth roughly 4.5 yards by 2 yards. Or alternatively, approximately 4.5 yards of double width fabric.