Are you saying you have never had a Mac before, if you have been a Mac user at some point then you don't likely need classes unless it has been many many years. There are many YouTube tutorials for new Mac Users, for example https://www.youtube.com/watch?v=egK5BKEn87c. If there are specific apps you want to learn about that come pre-packaged with Mac OS such as iMovie, Numbers, etc. you can find Apple's users guides. To easily locate them use Google and search "iMovie User Guide" for example.
If you are new to Macs the Apple Stores do offer courses however I don't know if they have them on-line. You will need to visit your local store and ask or you can check Today At Apple which you would also Google to find out what is happening in your area.
If you are moving from MS Windows to your first Mac, for the most part you will find Macs are more intuitive, do not need third party apps (such as Anti-Virus) to to maintain them and keep them running well. Most of what you already know is transferrable to a Mac. Also, Mac OS only needs to be kept up-to-date (check about 1x per month) and it is wise to restart the computer about 1x per week or so. Other than that just enjoy it and leave Mac OS alone.