Why when I turn on does it just stay trying to load?

The drive is having problems! The drive boot loader is getting loaded but it gets lost at that point.

You’ll need to find the grey disks that came with your system or find a friend who has an older Mac with macOS 10.12.x Sierra or older to create a bootable external drive for you. Then you can boot up under it. Or, Bring the two systems together so you can connect them together via FireWire so you can leverage your friends system as the boot drive. The for either method run disk Utility to check and fix your drive if you can.

References:

• Mac startup key combinations Using Option (⌥) to select external boot drive
• Understanding the Applications for Target Disk Mode
• How to get old versions of macOS
• How to use Disk Utility on a Mac