Squeaking coming from engine compartment

The belt is fucked, for one, you will need another new one. You've installed it either incorrectly or too loosely which has caused to jump inwards and trash itself.

Shit, I'm sorry, I've never really done any car work on my own. What little I do know was from my dad helping me and watching top gear. To remedy this do I just need to slip it back over the grooves or do I need to replace the belt entirely

Should replacing the belt solve my problem?

You need a new belt, that one is totalled. It needs to sit all the way inside the pulley, and where it hits a tensioner on the smooth side of the belt, inside the obvious clean bit as you can see from the pic you posted.

It's a bit of a colossal fuck up but I won't take the piss as everyone starts somewhere, and you shouldn't have done any real damage other than to the belt. Just get a new one, keep an eye on its alignment, tension it correctly and maybe watch a couple of youtube vidoes on it if you're still unsure.

A) I hope to christ you used the metal replacement elbows.

B) Spray a small amount of brakekleen on the belt at idle, should get rid of any grease pretty quickly

Pic related. I know how to make these things run for a long time.

The belt tensioner is automatic, so if it isn't tight enough, and you're sure you've got the right belt, then you need a new tensioner.

What's your oil pressure like at idle when it's heatsoaked in the summer?

The lowest I see my Oil Pressure is around 35-40lbs.

Also when I started it up, a warning message came on saying something like oil levels or pressure are low. I checked my oil and it was fine as was the pressure gage

You've probably got a bad sensor. They tend to flake out by intermittently dropping to 0psi. Hit the guage info button a few times until you see oil pressure and watch it for a while to see if it drops to zero and then jumps back up. Or just replace the sensor. Fair warning, you're going to need a big wrench.