There are several ways to clasp your collar at the back of your neck.  The possibilities are explored below. Pen Scissors possibly the following... Flat head screwdriver Rotary Punch Snaps Snap applicator Velcro X-acto knife
Step 1: If your collar is made from a belt, you may simply want to use the buckle as a clasp. On the non-buckled end, use a rotary punch to create a hole for the buckle where the collar is comfortably  secure on your neck.
Step 1:  Lay out your pieces.  You should have a piece of snap with a raised dot, which will fit into the piece of snap with a concave dot.  Because magnetic snaps are heavy duty, some may come with small metal re-enforcements.
Step 2:  Both snap pieces have prongs on the back (see photo in Step 1).   Place Part A on the collar base where you would like it to be, and strongly press the prongs down into the material.  When you take the snap away, you will have two indents in the material.
Step 3: With an X-acto knife, cut along the indent lines.
Step 4: Slide the prongs of Part A through the slits in the material...
Step 5: ...and slip one of the metal re-enforcers over the prongs.
Step 6:  Use a flat head screwdriver to bend the prongs of the snap outward.
Step 7:  Repeat steps 1-6 for Part B.  Remember that Part A and Part B go on opposite sides of the collar!
Step1:  Cut your velcro into two rectangles.  Attach the prickly side of the velcro to the underside of the collar at one end.
Step 2:  On the good side of the material on the opposite end, attach a small square of fuzzy velcro.  When the collar meets.