How do I do that? (Sorry I'm new)
Pending the arrival of the picture pigeon, two likely options:all these cables at the bottom where the psu goes
the way I read it, he hasn't put a PSU in yet, the shroud has cables in it before any PSU has entered the picture and he is curious what they do. Number 1 is possible, pictures or case name would let us know for sure.2. Thicker cables are probably for a modular power supply. You plug in the ones you need, and throw the rest in a drawer for future needs.