Click on the ‘Lesson Results’ tab in the Main Menu.  This will show you all your scores for every completed lesson.  If you click on the column headings, you can organise the scores into fastest first, slowest first, more accurate first, less accurate first etc. Repeated clicks on a column heading will organise the data in ascending or descending order.

You should also take a look at the ‘Key Report’ from the Main Menu.  This will show you a graph of your performance on every individual key and your performance against your target speed in the last lesson you completed.