From your fabric, cut:
1 big circle (this will be your biggest one - mine was the circumference of a plastic cup)
3 slightly smaller ones (by at least a cm)
4 even smaller ones (by at least a cm)
2 even smaller ones (by at least a cm - my smallest one had a diameter of about 2 cm)

Sort the four flowers as such:
1 biggest - second biggest - third biggest
2 second biggest - third biggest
2 third biggest - smallest

Making five flowers total :D

Sew the flowers together by sewing a circle through all of them and gathering the thread.

Sew onto headband by looping the thread around the teeth when you sew
or
Glue it to the headband using super glue or a hot glue gun

Arrangement: Biggest in the middle, then descending sizes to the right and left
You can place the flowers on the side of the headband, or for a more princess-y look, you can place them right smack on the top