I learned by researching about each type of modality on it's own. Like you can research LEDs or phototherapy on Google. NASA has done a lot with this technology. It's become quite comonplace to see LEDs and low level laser therapy or LLLT used in medical settings and with chiropractors and physical therapists etc. There are TENS units for pain reduction, zappers/blood electrification devices for getting rid of infections/parasites. Magpulsers are use for pulsing lymph, pain reduction, and rejuvenation. There are water ozonators and Colloidal Silver makers as well for getting rid of pathogens and other benefits. There is so much out there you can spend almost a whole day researching each modality. Start with what you can afford and build from there.