If you have a trauma first aid kit:
For life-threatening bleeding from an arm or leg and a tourniquet is available:
Wrap the tourniquet around the bleeding arm or leg about 2 to 3 inches above the bleeding site (be sure NOT to place the tourniquet onto a joint - go above the joint if necessary)
Pull the free end of the tourniquet to make it as tight as possible and secure the free end.
Twist or wind the windlass (rod) until bleeding stops
Secure the windlass (rod) to keep the tourniquet tight.
Note the time the tourniquet was applied.
Note: A tourniquet will cause pain but it is necessary to stop life-threatening bleeding.