Ixeg 737300 Liveries -

Inside you should see:

The IXEG 737-300 models engine variants. Some liveries require the "shorter" or "longer" CFM cowl. Check the livery’s readme file; you may need to change the engine type in the IXEG menu. ixeg 737300 liveries

Installing skins in X-Plane is straightforward, but the IXEG has a specific folder structure: your chosen livery (usually a .zip file). Inside you should see: The IXEG 737-300 models