What did I do wrong?

Hey, I have a intel westmere stystem I was trying to make a hackintosh out of I followed the (guide name) and got my usb but it did not show up as a boot option in the boot menu. So I tried it on my laptop (so I could install Mac OS in a external drive and move it over to the other system) and it booted fine (both are dells) and it booted into the drive but threw this. I don’t understand any of this and I’m new to hackintoshing so idk what I did wrong. Can y’all help me?