In my Xubuntu 18.04.05, I'm trying to set up my digital piano in order to record it in OBS and create a tutorial for a friend .
I'm not really skilled in such programs and I hit the wall.

Separately, I'm able to run VMPK with Qsynth to see a virtual keyboard and hear the sound. However, once I use OBS (also not a skilled user), I can't get any sound into/out of it.
Yes, I've added the sources (mostly just a hit and miss) but still no luck.
I need to add my regular microphone and the sound from Qsynth/VMPK (I'm not even sure which one is the sound source, it should be Qsynth but I set the sound in VMPK).

However, why I stopped trying .... VMPK/Qsynth use Jack (not sure what that is but I get it controls sound at a different level) .. and when I used to use Jack for other experiments, other sound on my PC stopped working (background music or video).. so I figured, it could be the same problem (function). That I cannot run all these things together.

The final product should be - the virtual keyboard, my hands on my real keyboard from a PC camera, the virtual piano sound and my microphone.
(Or maybe... I might use an audio cable to record the real piano sound)

Any thoughts?