[Pathfinder help]How to level up characters in the standard character sheet

Hello everyone, I've been trying to help my players generate pathfinder characters using the standard pathfinder character sheet as provided by Roll20 itself, and I've been having some issues figuring some stuff out. I want my players to start at level 1, but the character sheets have the "level" in a grayed out box at 0, and I quite frankly have no idea how to change that up to 1. Can anyone help me?

If you scroll down on the core tab of the sheet, you'll find this (I've collapsed the intervening sections: The level that is in the greyed out box at the top is the total of all your class levels. Enter the applicable class info, and it will update.