can be purchased at any framing shop, and also at most major craft stores. They are simple little push-pin like devices that hold the artwork and backboard inside a frame.
They can be pushed into position around the artwork using a glaziers point tool, or by some other hard object, like an aluminum bracket, which is pictured below.
Once the points are in you can use brown paper and more double stick tape to cover and seal the back of the frame. This is optional, and doesn't effect the finished product at all, but if you're giving it as a gift it can really class things up a bit.