Carla, a couple hints to add to Tom's description;
-First thing: before you shut down all your water supply, fill a 5 gallon bucket with water you might use to wet a sponge or rag with, rinse your hands, or in need of fire. When soldering pipe in joist spaces, etc. be sure the area is clear of cobwebs, lint, or other quick sources to spread fire.
-When heating/soldering near framing or wall cavities, be especially sure to remove as many dangers as possible, & watch for any flare-ups while you work. As you are buying your supplies, you can get a plumber's fire resistant cloth shield if you feel you will be working in areas you might need it. It's usually about a foot square, and can be placed between flammables and your work.
- do not directly touch the cleaned joint areas before or after brushing with flux; consider these areas sterile. Use a PASTE flux, as Tom mentioned; if you see a liquid flux that claims to be wonderful & easy, pass it by...trust me.
- apply the heat to joints being soldered from behind & on the fitting, i.e. if you are soldering a 90° elbow, have both pipes entering & leaving the 90 in place (to be soldered at the same time), and aim the tip of your flame at the outside corner of the 90° fitting, not directly on the pipes or joint face. Always apply your solder on the opposite side from the flame of the torch.
- do not worry that you may find yourself needing to apply your solder from a point on the bottom side of a pipe vs. the top; the solder is drawn into the joint by capillary action and will fill any properly fluxed area, even if it's above the point of entry.
- Commonly, when the flame that flares up around the pipe/fitting suddenly begins to turn green, NOW is the time to begin applying solder into the joint. It's also the point you want to start removing the flame intermittently so that you do not overheat the joint.
- If you hear hissing in the pipe, or a boiling sound, you still have water in the pipe; this water is "drawn" to the heated area, turns to steam, and will create pressure blasting out through the joint you are trying to solder. To minimize the possibility of this, once you've shut down the water main open all faucets in the home to drain the system, then use a wet/dry shop vac to either suck or blow the pipes clear after you've cut them open, and before you clean/flux them.
- and finally....buy a couple extra fittings and pipe length to try all this a few times to get the hang of it.
Good luck, Carla
Personal note to Tom...I hope we've done Raymond proud ;-)