G'day Music, and Welcome to linux.org
You probably don't need online classes as such....here at linux.org you will find most/all of the help that you may need.
Start by telling us a bit about you....and where you are up to at the moment
Are you still using Windows?
What sort of desktop/laptop?
Make and model/be specific....more info the better....ram memory, ghz, hard drive/s
What do you wish to do ?...be specific !....run Linux on its own with no other OS (operating system) on the pc...or do you wish to run a dual boot system where you might have windows as well as Linux on the same pc (more complicated)......or even two different Linux versions on the same pc....
The simplest approach here is to just have one Linux distro running on its own......eg Linux Mint
At this time pay less attention to the Terminal and using commands etc etc....(that will come later) and just concentrate on learning to navigate Linux. That is the simplest approach.
Many people will chime in here and their advice may confuse you......try to sort the wheat from the chaff
The simple approach is to "burn" a linux iso (this is a group of files containing all that is required to boot Linux) to a thumb drive (pen drive , usb drive...approx 8 gb....or even 4gb will do) and then alter the boot sequence on the pc/laptop so that the pc boots (starts) using the info on the thumb drive
Simple as that....you are now using a LIVE version of Linux Mint.
LIVE means that any changes you make such as setting up Firefox browser or making alterations to the desktop or etc etc etc etc....will NOT survive when you shut the pc down or reboot. In other words
The LIVE version is a TEST version for you to decide whether or not you like the linux Mint OS that you have been playing with. You can do anything you like with that LIVE version....anything at all.....and you will do no harm to your pc or any other OS that is on that PC.
Why, I hear you ask ?....because the LIVE version actually runs in the RAM of the pc....NOT on the hard drive.
If you like the OS (linux mint) and decide that you want to occupy the entire hard drive with that OS, in other words have JUST linux Mint on the pc...(NO windows)....then you simply click on the INSTALL Linux Mint icon which is on the desktop, and follow the prompts. BE WARNED....this will WIPE the hard drive clean....and install Linux Mint ONLY
All very informative I hope. If you decide to stay with us and follow this course, please give us some info, starting with what I listed above.
Additionally, do you have an external hard drive that connects to your pc/laptop possibly via a usb lead ?