There have been several threads on harmonics on this forum--hopefully you can find them. It's best to get some level of mastery in "Astrology 101", though, before you get into harmonics (Astrology 301 or 401) because they requires a higher level of abstraction in using astrological symbols. If people are still trying to get their heads around all of the data bytes on the regular natal chart, looking at harmonic charts probably is premature.
Essentially harmonics are like aspects. The 13H chart is the same as dividing 360/13. Where you see conjunctions in a harmonic chart that you don't see in the natal (or radix, or 1H chart) you basically have the aspect/harmonic in question. Some astrologers think the 13H chart sums up the natal chart with a different perspective; others attribute a degree of Uranian disruption to both the 11H and 13H chart.
The 2H chart simply indicates oppositions; the 3H chart, trines; the 4H chart squares; the 5H chart, quintiles; the 6H chart sextiles, the 7H chart, septiles;and so on.
But there are no houses in harmonic charts, and many astrologers think signs are worthless, as well, because these charts really are abstractions. Then you would read aspects sort of in the same way; except in recognizing that you view them through the lens of whatever the root meaning is of the harmonic in question. For example, if a 13H chart shows some rebel or disruptive proclivities, a square would show how the involved planets feel sufficiently stressed or challenged that they need to manifest their energy in some way.
Some people do not resonate to particular harmonic charts. If you cast them and see no conjunctions, then the individual really doesn't have the aspect in question.
You can create charts for whatever harmonic you want on the Astrodienst "free charts" pages.
Vedic astrology also uses harmonic charts, but I've not studied this system.