Now, the SOLDERING LESSON....
First and for most, it needs to be HOT, the hotter the better, plug it in before you begin and by the time you are ready to use it, it'll be GOOD and HOT...
Next, the soldering iron needs to be in good shape for good soldering, NEVER, NEVER file or sand a soldering tip to clean it... once hot, a damp paper towel or sponge "should" clean it, if it is in half way decent shape... If you can't get a nice bright silver/chrome look from it, consider some fine seel wool, if that doesn't do it, a new tip or iron...
Now, you need to "tin" the iron, which is nothing more than melting some solder in the tip, this needs to be done often to keep a thin layer of solder on the tip. The tinning acts as a conduit for heat transfer. Clean the tip often on the damp whatever you have and re-tin after each cleaning...
Depending on the wattage of the iron and the thickness of your solder this can be easy or difficult... Thick solder for sweating copper pipes is not recommended because it removes a lot of heat from the iron... It CAN be used, but it's better to have thinner "electrical" solder.... And "flux core" solder is a good idea as well...
Flux it a acid/rosin mix that helps strip impurities from the wire and solder and makes the job LOADS easier... if you don't have flux core solder, little tins of flux can be bought near ANY solder in the store...
Now, now that you have your first pair of wires twisted and your iron ready, get set to solder...
Tin the iron and give it a quick "flick" toward the floor (doing this in the house in the carpet/vinyl flooring NOT recommended) to remove the excess...
Place the tip of the iron on the wire for a few seconds, let the heat rush into the wire, now touch the solder to the iron, right where the iron and the wire meet... If you are hot enough, the solder will melt and start flowing INTO the wire via capillary action... once you see the solder flowing, you can move it (both the solder and the iron) around a little on the wire, feeding in solder until you see the connection is completely silver, remove the heat and let it sit for a few seconds...