So new, so lost

All I want is to have my lvl 60 priest heal my low level mage. That's it. And I can't figure it out to save my life

They can't be partied since it will kill my xp. Why is this so hard for me to figure out? ugh.

[lax]

There's no requirement that you are in a party.

But you haven't said what you're stuck on, so we don't know why it's so hard for you to figure out, or what to tell you to do differently.

Generally speaking, follow the WoW: Quicker Start Guide. If you don't want both windows to use 1 through = buttons, un-tick the box on the last page of the Quick Setup Wizard. You should follow the guide including the part that says to press a specific key to invite your team, for the first time through the guide. This is because the guide is written with troubleshooting built in; if that part fails, we know the rest of the guide is going to fail, and usually why it failed as well. So if following the guide top to bottom doesn't work exactly as it explains, either stop and ask for help, or read the solutions detailed right in the guide.

Assuming your team will successfully launch and the follow/assist are tested to be working, you can move on to configuring other pieces for healing and such.

You can use the Mapped Key Wizard to add custom hotkeys to ISB42 - Custom Hotkeys, such as a key for your level 60 priest to heal your low level mage. The trick to making it easy is to already have a button set up in the game that heals your low level mage, and then you have ISBoxer press that button when you press your custom Hotkey. You can press a different key than it sends (the wizard calls that a Key Re-Map).

If you want to get even fancier with healing, you can heal the way that healers do, with unit frames. MiRai's Healing 101 video will help with that. https://www.youtube.com/watch?v=6qHo0FTuGV0

That's about it.