Tassels can be used to decorate anything, and is very easy. I'm going to show both a hand method and another time I'll do a tool method, with how to make the "tool." Both work for tassels, and the later tool method can make fringe as well.
Yarn or crochet thread or embroidery floss
A crochet hook
Step 1: The Base String
Cut a piece of yarn about the length of your finger, or a little longer.
Lay it along your finger ( see first 2 photos) holding it in place with your thumb. I'm right handed, and place it on my left hand. Reverse if you are left handed. I'm showing this part with contrasting yarn, so you don't get confused.
Step 2: Winding the Tassel
Take the end of the ball of yarn, and lay the against your hand perpendicular to the first piece of yarn, with the end at the bottom by your pinky, and crossing it over the first string, holding both in place with your thumb. ( see second 2 pictures).
Wrap yarn from the ball around your hand, in the same direction as you have begun, crossing over the first string in every round. Don't worry if the first string slips a bit, as long as you can pull it back up, you are okay.see next two pictures
You'll want to wrap at least twenty rounds, more if you want a bigger tassel. See next picture.
Cut the yarn from the ball at the bottom, by your pinky, keeping the yarn on your hand. See picture 8.
Step 3: Securing the Tassel
Pull up both ends of the first piece, making a loop around the wrapped yarn, which should gather tighter inside the loop. Keeping the ends of the first piece together, remove from your hand and tie the ends off tightly. If you can tie them with the yarn still wrapped around your hand even better, but that takes a lot of practice. See next 6 pictures.
Step 4: Making the Head
Take up the ball of yarn again, and wrap several times around yarn just below the tied off end, leaving enough of the starting end sticking out that you can tie the ends together. I'm showing this first in contrasting yarn, so you can see it ( 4 photos) then repeating and finishing with the original color, so it looks right (7 photos including tying off).
Step 5: Opening the Tassel
Slip the scissors through the bottom loops of yarn and cut them in half(2 photos).
Trim to an even bottom edge.
Step 6: Finishing Touches
The first piece of yarn can be tied into another loop for hanging, or used to sew the tassel down. The ends from the top wrap can be pulled to the inside with a thin crochet hook.