I believe there are educational materials available through this forum/website about medical billing, and there are organizations, such as the MAB, that also have educational opportunities. You can of course always Google "medical biller training" or something along those lines, and see what pops up for materials to educate you.
Numerous vocational colleges offer programs in medical billing/coding also. These are costly, though. And none of this is a guarantee of a job, unfortunately, because so many people are pursuing jobs in this field. Remote/at home work is basically impossible to find for someone without experience in billing. It is a tough market out there.
In your favor, you have medical terminology experience. If you were looking at coding, that would be especially helpful.