And to answer a question from earlier in the thread:
Flux is used to help make solder "flow" onto the hot sides of the joint. The flux melts at a lower temperature than the solder, and it basically cleans the impurities/oxidization/whatever off the metal, which lets the solder bond against the metal. It's usually some kind of pine or spruce rosin. Exposure to fumes is not really good -- beyond the obvious things it would do to you like irritate your lungs, it makes you more sensitive to the fumes, which sets up the kind of feedback loop you want to avoid on your body. Have a window open or a fan.