Run a 2-7
Have a complete disaster run.
Go to WoWHead and read up on the trash and boss where the problems occurred.
Repeat.
You’ll learn enough of the basics fairly quickly.
The big thing is just don’t get bent out of shape or take anything personally. On bad runs you’ll run into people not emotionally equipped to deal with failure. Don’t make it worse by being the person not emotionally equipped to deal with valid or invalid criticism.