Clasps or closures can vary with each necklace and bracelet. Many bead designers buy clasps to finish off their work.
The clasp on the left is made with using a soldering torch and thick wire. If you do not choose to do this -- you can create a clasp with 14 g or 16 g wire. This size of wire will be stable enough to hold your piece together.
Using your round nose pliers bend the wire around itself and the clasp is then cured with your hammer. File your ends for a good closure.
These are simple clasps and with more practice you will find one that suits your work. Naturally, you will add jump rings on both loops of your wire work clasp. One to use as your closure and one to connect to your piece.
Remember your Working With Wire rules:
Always use the correct tool for what you are working on.
Use your fingers to move the wire while bending, and your tool to hold your wire.
Always cover the top of your wire when cutting off an end. Snips of wire have been known to fly across the room.
Wear safety glasses when cutting wire.
Remember that your fingers will be sore when you begin to bend wire, don't give up, it gets better with time. You might even use a band-aid on your finger and thumb while working in the beginning.