Disconnect the saw from its power source.
Rotate the saw blade shield to the upward position so you can access the hex nut on the arbor that is located in the middle of the blade. If you choose, you can place the saw on its base and push it downward to lift up the blade shield.
Press the blade lock button and rotate the blade by hand until it locks into place.
Loosen the hex nut using the wrench supplied with the saw, and remove the nut from the arbor.
Pull the blade off the arbor. Take note of how the original saw blade rests on the arbor. The saw blade teeth go in a specific direction.
Place the new blade onto the arbor in the same position as the old blade. Thread the nut onto the arbor and tighten it with the wrench. Release the blade lock and lower the shield back into place.