To upgrade your staff, go to the Staff Overview screen and select a staff member you would like to upgrade. This will open their details page. In a staff member’s details page, you'll find three attributes that can be upgraded: Skill, Empathy, and Dedication. To upgrade these attributes, you'll need to have a sufficient amount of training cards of one of the three aforementioned abilities and sufficient cash to cover the cost of upgrading. If you have enough of both, then you can press the Upgrade button and the attribute you've selected will improve.