Place the ends of two pieces of the poster frame together to form one corner.
Attach a frame clamp to the corner to hold the pieces together.
Turn the pieces upside-down so that their backs are facing you.
Place one V-nail over the two pieces so that the wings of the nail are on either side of the seam. Place it about 1/2-inch from the inside corner of the frame.
Insert the V-nail into the wood with a hammer.
Place a second V-nail with its wings straddling the seam, but put it about 1/2 inch from the outside corner of the frame.
Insert the V-nail into the wood with a hammer.
Insert other nails as needed to attach the corner. For every two inches of frame width, use at two V-nails.
Nail the other poster frame pieces together using the same method outlined in Steps 1 to 8.