If you are curious about different kinds of framing options, check out my Framing 101 post first.
Float mounting is a way of framing so that that edge of your paper is visible and not cut off by either the frame or the matte. It enables the edge (most likely a deckled edge) to be seen clearly. Highlighting this part of a painting or print can make all the difference when it is hanging on the wall.
There are two ways to achieve this look:
Cut a window matte (or ask your local framer to do so) just slightly larger than the print itself and then back it with the same color matte board as the one you used for the window matte.
Simply stick, using archival, double stick tape, your piece of artwork to a matte board backing that is larger than the artwork itself, allowing the edge to be highlighted.