There are many soldering guides on MAKE and on the Web, so we will only summarize it here. The basics of soldering are as follows:
If you are doing through-hole soldering, you will heat the iron, and then hold the iron to the lead you are soldering and apply the solder to the iron, letting it flow onto your joint. Finally, you wick away excess solder.
If you are doing SMT work, you will want to place the board on a hot plate to bring it up to temperature. You will place solder flux onto the pads, and then tweezer the part on top. You use a heat gun with a narrow nozzle to melt the solder and have it flow into place. Finally, you wick away excess solder.
The tools and gear you need include a medium-quality iron. Avoid the dollar-store specials or $10 Chinese eBay specials. You want a decent iron that has variable temperature settings. For the heat gun, choose one with a small aperture, and purchase a set of nozzles that let you narrow the flow of air further. SMT solder paste, consisting of the solder and flux, is usually refrigerated and is perishable.
Be careful with expensive, breakable parts. Primarily, this will be the solar cell wafers you fry. Soldering the solar panels required I learn the new soldering technique of reflow soldering, where you paint solder flux, and then just heat the entire material. I ...