Look for the "SparkFun-Boards.lbr" file. Inside this library, you will find the "Pro Micro" part, which includes both the schematic symbol and the physical footprint for your PCB layout.
: Since the Pro Micro sits on top of your board, ensure no tall components (like large electrolytic capacitors) are placed directly underneath it. Common Library Sources arduino+pro+micro+eagle+library
This is the footprint that will appear on your PCB. Look for the "SparkFun-Boards