Now that I have backed up my old IPhone, how do I load this data onto my new IPhone?

I assume that you are backing up with iCloud, so this will tell you how to set up the phone using the iCloud backup.

Use iCloud to transfer data from your previous iOS device to your new iPhone, iPad, or iPod touch - Apple Support

Essentially, you have to start from scratch on the new phone meaning that if you have already set it up, you have to erase it in the settings to start over, then restore the iCloud backup when presented with the option to do so. If you have the set it up yet, just turn it on and follow the prompts.

If you backed up with iTunes, this explains what to do.

Use iTunes or Finder to transfer data from your previous iOS device to your new iPhone, iPad, or iPod touch - Apple Support

Hi:

If both your phones are relatively recent models, you should be able to use Apples Quick Start migration utility.

https://support.apple.com/en-us/HT210216