Here is another way, if you want it, using "string theory":
Harmonics or overtones are the simultaneous vibrations above the fundamental, for any vibrating string. They are part of the sound, timbre, of string instruments, without them a guitar would probably sound like a sine wave synthesizer.
For example if you play A# = 466 on a piano, then the overtones would be rougly, in Hertz:
~466*2 = 932
~466*3 = 1399
~466*4 = 1864
~466*5 = 2331
Notice the pattern? The overtone series, as it is called, is infinite, but overtones above 20000Hz are of course inaudible, and the amplitude (meaning volume) decreases progressively.
Well, let's get to the point. You can construct chords and scales from these frequencies, in fact our 12-tone system can be derived from the overtone series (somewhere in there is a half step interval). You could construct a chord from the frequencies i provided (check the corresponding notes), which would match up imperfectly with the piano (other factors are involved), but the guitar would also be producing its own overtones. Using the lower overtones in the series also gives you more consonant intervals.
This approach, if it works, would also likely sound bad in a mix and is not recommended, my recommendation is power chords or the appropriate triad (e.g. major) for the musical context (which of course all can be found in the harmonic series). Good luck!
Edit: this is probably high-flying for somebody who has "just started learning", don't think of it as essential knowledge.