With the clipper facing you, place the pad of your thumb on the blade and swiftly push the top of the blade away from the clipper. This will make the blade '"tongue" or "blade assembly" open and you can slide the blade off. off the "tongue" and replace the new blade on the "tongue". With the "tongue" open, turn clipper on and then push the blade towards the clipper (shut), this will ensure the proper engagement of the blade on the driving tip. If you have any further questions, please call us at 800-830-3678.