pc hard drive

I've been trying to install these HDDs for hours now, but even after watching several tutorials, I still don't understand what I'm supposed to do. I've tried connecting them, but the cables either struggle to connect or just pop off because the wires aren't long enough. All I really know about...

System specs Nvidia 680i lt sli Intel e8600 @ 3.3gh 8 gb ram 800mz Nvidia gtx 550 ti 1 hhd 500gb 7200rpm 1 cd/dvd combo Will a 550w ultra x-connect 2 power it all. I'm asking because the gpu i got says it needs 24 amps and the 12v. But mine says 18 amps on 12v1 and 18 on 12v2. Does that mean...