welcome to the Zynthian world !
To answer your question : to make chiptunes on the Zynthian, the best “theorical” way is to get a LV2 plugin emulating one of the chip used for this kind of songs.
In a very simplified view, you have mainly 3 families of soundchips used for chiptunes, each of them having its own characterictics :
- the AY-3-1015 chip
- the 6581 SID chip
- the YM3812 (aka OPL2)
As far as I know, the AY-3-1015 has never been ported to LV2 format.
The 6581 and the YM3812 have been both ported to LV2, but I have never tested them on the Zynthian (or any other Linux machine). So theorically, they could be compiled and run on the Zynthian
However, since you say you are a beginner, you would then not recommend you to go in that direction.
In your case, I think the easiest way (but not the most flexible) is to download samples and/or soundfonts from these chips (there are thousands of such samples available on the web) and load them either in LinuxSampler or FluidSynth.
I have made a tutorial to explain how to load your own samples in the Zynthian, this may hlep you. The tutorial can be reached from the Zynthian wiki page or from this link