I'm assuming your PSU is modular (PSU has little plugs you can put cables into). Look at your PSU's manual and it should tell you where each plug goes. Or in most cases, the plugs are color coordinated.
Also, with most PSU's nowadays, you can plug in multiple devices with one plug. This is called daisy-chaining. This is normal and 100% safe, you have nothing to worry about.
The red slots say GND (assuming ground) and v2 on them. I think I need to plug them into my PCI slots for my video card. Its a Sapphire 7870 if that helps.