The other way to improve your Excel also performance skills from your superior. You can approached your Superior that you want to improve your excel and possible to give simple to complicated data for you to analyst and from there you can improve more by daily basis. Trust me is worthy to learn direct with the superior as I always do that same thing. P/S: Do not forget to take notes (write in your diary or book and keep sample for your references)

Hi Wong! Usually I would take a look at youtube tutorial and sometime I google whenever I don't understand a term.

There might be classes tho.