Modal Synthesis?

How can I procedurally create sine waves, combine them and play them?

I have been trying to follow the FMOD documentation but can’t figure it out.

I am totally new to sound and I don’t know how to even begin to approach the implementation

This is a rather large and complicated project but is doable and I can point you in the right direction.

In the FMOD Studio API installation examples, the Core API example granular_synth can show you something similar to what you are describing. However, instead of playing multiple sound files, you can use an oscillator DSP to generate the sine waves you need.