Have been having trouble finguring out where to insert the PSU into the Apex PC-389-C case. This is my first time building a PC so I am naturally confused, I have not been able to find any sources to help with the problem.
Well the PSU goes in the top of that case. I am not sure what you are having a problem figuring out? The case has a big cutout in the top back of the case for the PSU and is attached with four screws that secure it to the case.