Unfortunately, just having taken a class isn't usually a good indication of knowing the subject matter. For example, I took many high voltage courses (and got As in them!) and I remember very little from them - certainly not sufficient to use for anything practical.
So, you can add courses on LinkedIn, but be aware that course experience may not be valued as much as you think. However, it still shows that you have some exposure to the subject matter and may perhaps pick it up quickly in your work.
As jcmack noted, practical hands-on experience is generally more valuable. In some of my hiring experiences, I know that we've overlooked slightly lower grades (than our official/advertised cutoff) in lieu of practical experience earned either through group or hobby projects.