If you want to get a little bit more familiar with vim, just type
vimtutor in your terminal. It's likely that you already have it. If not, check with your OS package manager.
The tutorial is basically a text file opened in vim that you will navigate and edit as you read the instructions. Very meta! :)
The authors say that it should take 25-30 minutes to complete but you can split your learning into even smaller chunks: say, one lesson each day (there are 7 lessons in total).
And finally, I'll repeat an advice from the tutor:
NOTE: Remember that you should be learning by doing, not memorization.