I don't find it complicated, either. Click on Reports, then Month-to-Date. There, in column 1, you see how many books you have sold this month, in column 2 how many were returned, and in column 3 the net sales for the month. If you are foolish enough to commit yourself to selling only on Amazon, you will see other columns too, which don't interest me so I don't know much about them.
Since this is February 1, you might also want to select for the previous month.
Of course this has nothing to do with payments. That's a whole other interface, which again I don't bother with. The payments almost always arrive on the 29th of the month, so a few days ago I got my payments for November. At the end of this month or the first of March, I expect my December payments. And on the 29th of March I will expect my January payments. Etcetera etcetera and so on and so forth....
(Don't trust KDP to publish a print edition. Don't trust CreateSpace to publish an ebook. Each does one thing well and the other thing poorly.)