A harmonic balancer goes on the opposite end of the crankshaft from the flywheel, and is a tuned resonant device - usually has inner and outter masses, with a spring system connecting the two. (The spring is often a compressed sheet of rubber). The purpose of the balancer is to anti-resonate with the natural torsional resonant frequency of the crankshaft. They are only used or needed with long, whippy crankshafts - especially an issue with straight-six engines.
Nathan, to move forward from Jay's lexicon and get you a grounding in modern 2-stroke carburetors (usually more difficult to understand than 4-stroke ones) you might try reading this:
http://wem.walbro.com/distributors/servicemanuals/WAseries.pdf
You will probably have questions (for example where do the 'engine impulses' that work the fuel pump come from. The answer is 'crankcase compression', which only exists in crankcase-induction 2-stroke engines) but those can easily be dealt with as they come up.