Replacing (and perhaps upgrading) bad capacitors within a speaker system?
You can replace them with pretty much any capacitor that has the exact same rating. It will be relatively easy to replace them, and can be done with any soldering iron that can adjust its temps to under 400*f coupled with solder that has a similar melting point. Preferably you want an iron that is regulated at the tip (not just a dimmer), but for low-power electronics like this that really isn't as much of an issue.

You'll need to desolder the joints, which just consists of heating them until hot enough to pull out of the holes. If you can manage it, put slight tension on the cap while you heat the solder so it will come out as soon as it's hot enough. 

When putting the new one in, make sure to apply a light amount of flux to the joint, then put a small amount of solder on the iron, then touch the dab of molten lead to the joint. If all goes well, it will transfer from the iron to the board. After a successful attempt, cut the cap leads as short as possible. Alternatively, if you feel comfortable, pre-cut those leads to protrude about 3-4mm from the back of the board so that the entire lead is encompassed by the new solder. 

Here are some recommended supplies:

376* melting point solder
Waterless Tip Cleaner
Aoyue 937+ Digital Soldering Station