On a resume itself, you would not list classes taken. Keep it just like your past resumes (I am assuming that you are second degree/career). You list your edu and your work experience. What I would add for your purpose is a very condensed bulleted section under each job listing "scope" and "skill". With this, healthcare people (who DO NOT KNOW THE OUTSIDE PROFESSIONAL WORLD EXISTS!!!!!) can parse what the heck you did at your last jobs (otherwise they will have no idea).
So. For a cover letter, I'd rec that you just go for the job you are applying for and extremely briefly and concisely state jobs and their associated skill/scope directly pertain to this one you are now applying for in healthcare.
Having said that, you need to not elaborate too much - especially if you highly achieved in your last profession - you will intimidate and write yourself right out of a chance at a job. Also, you might, try for jobs such as floor secretary, etc. But, it might behoove you to take a course in medical terminology
to assist you in your transition. Also, you can try craigslist for jobs for "Front Desk" or even "Receptionist" for MD/Dental offices/clinics (work is the same) as you're past experiences might be given more weight. Now, don't look down your nose at these jobs as they can be quite complex and exhausting. Often times "Receptionist or Front Desk" means you are the OM for the practice for all intent and purpose. You are the money man/woman, you are the one who files/resolves all insurance issues/patient issues, you are the one who does prelim triage and scheduling as well as handling/resolving all incoming to the office from hospital/other MDs/radiology, whatever may come.
In some ways a CNA job has much less responsibility as you would have set tasks: vitals, feeding, pottying, bathing, answering call lights, etc. - which, is very physically exhausting in nature, but you do not assume the flow of an entire practice.