How do you solder a copper pipe end?

Clean the end of the pipe and whatever kind of fitting you are putting on it with either steel wool or fine sandpaper. Put flux on both pieces covering all the surface where they will be joined. Use a propane torch and heat on one side of the fitting and touch the solder on the opposite side. When the solder gets hot enough to melt, it will be drawn to the heat source. By having the solder on the opposite side from the heat you know there is solder completely around the fitting. Let it cool before handling.