Stand it upright and fill the core with water to protect the solder below where you are soldering.
You need an acetylene soldering torch to do this successfully the first go round. Its a small tank which only has acetylene. It has a flame tip which provides excellent control of where you want the heat to go.
Keep the heat moving as you heat up that nozzle all the way around until the solder melts when you touch the solder to the metal.
