Assuming you would like a step-by-step guide on how to change the blade on a reciprocating saw:
1. Unplug your reciprocating saw or remove the battery.
2. Locate the blade clamp screw and loosen it with a hex wrench or Phillips head screwdriver, depending on your model of saw.
3. Insert the new blade into the slot with the teeth pointing in the correct direction (toward the front of the saw).
4. Re-tighten the blade clamp screw until it is snug but not overly tight.
5. Reconnect your power source and test out your new blade by making a few cuts on some scrap wood before beginning your project.