Remove the old blade. Lift the blade until it locks into an upright position. Look for a tab or button that you need to lift or press to remove the blade. Then, slide the blade off the arm. Gently lay the arm back down on your windshield so it doesn’t snap back down and crack your window. Repeat with the second blade.
Install the new blade. Read any installation instructions included with your new blades. Putting on the new blades may be a little more difficult than it was taking off the old one, but once you get it into position, it should snap into place. Repeat with the second arm.