Solder copper pipe joints by applying flux, twisting the fitting to spread the flux, heating the fitting with a propane torch until the flux bubbles and touching a piece of plumber's solder to the joint. The flux draws the solder into the joint to create a watertight seal.
Cut the pipe to length, and attach it with the appropriate fittings. Use a tubing cutter, and remove any burrs prior to assembly. Use emery cloth to clean the outside of the pipe and inside of the fitting for a strong joint.
Apply the heat from the torch to the fitting instead of the pipe. The hottest point of the flame is at the tip of the inner blue cone, or about half the length of the flame. When using a torch, provide heat protection for the surrounding areas. Bubbling and steaming flux is the indicator that the fitting is hot enough to melt the solder and pull it into the joint. Solder all the pipes in a fitting while it is hot.
Once the joints are cool, turn on the water, and leak test the system. If any joints leak, turn off the water, and drain the lines. Heat the leaking joint, and separate the fitting from the pipes. Reclean the pipes and fitting, apply new flux, and solder the joint again.