Power Supply Pcb How Do You Design A PCB?

How do you design a PCB? - power supply pcb

I design my own board. My goal is the power of 3 motors on my computer with the DB25-pin connector and a power source. My only problem is they have no idea how to make a design. I do not know, not one of the other ingredients. Has anyone any idea how to recognize and know what to do and what elements are necessary components for an upgrade? Thank you!