Kind of makes you wonder how you ever graduated third grade, doesn't it?
Don't worry, this stuff has humbled most of us at one time or another, especially starting out.
Just keep working with it and give yourself some time. You'll catch on.
By default, MC6 scans for VSTs when you start in up.
If this is turned off, you will need to start a scan from the Plug-in Manager.
Just being in the folder isn't enough. The VST has to be registered within the program.
Also, Addictive Drums may be in a sub-heading. Look for listings with arrows next to them.
I'm not sure if copying the .dll is a good idea. It's ok to move one, though. A lot of people like to do it that way.
My personal preference is to let the VST install to its default folder, and add that folder to the list of folders to be scanned.
Congrats on the MIDI keyboard. That will prove to be a hugely worthwhile purchase.