Qlik Sense February 2020 - Loading and preparing data from Microsoft Excel spreadsheets

I think it goes to fast. If you do not have a recommendations what did you click then. I guess not "apply" but it is hard to see what you clicked. If think beforehand you should have some introduction as to what you want to achieve. And what does "most important" file means? Is is sales, customers, items? Pls explain. And what If I load it wrong order.