The ovular metal ring above is called a "jump ring" or "split ring", they can also be circular. Jump rings are used to connect one object to another. In this case, they are connecting your crochet chevrons to the metal clasp. There is a split in the middle of the oval which is used to twist apart the two sides. Instead of pulling away from each other, you will generally be using pliers to twist the sides in opposite directions. You can slip one end through the crochet chevron, then twist the jump ring back together.
For jump ring instructions, click here.
You can also make your own jump rings!
Click here to learn how to make jump rings with 18g wire using a jewelers saw.
Click here to learn how to make jump rings from wire and wire cutters.
For more resources on jewelry, be sure to check out www.beadingdaily.com