Raidmax vortex 402 and a corsair 450w psu PC won't boot!

Hello,

I have recently bought the raidmax vortex 402 and a corsair 450w psu, for 2 days I have been transfering all my parts from my Alienware x51 r2, only tonight have we got it to boot, but then a msg said that there was no hard drive so we plugged it into the mother board and that didn't work so I unplugged it from the hard drive and mother board and now it won't boot at all, I was working on tile so there was no static.
My pc
The Alienware motherboard I'm not sure of the name
16gb ram corsair vengeance
Sapphire Radeon nitro dual-x 4gb
Intel core i7 4770
Western digital 1tb hard drive

Ps, This is my first time ever transfering parts, please make your answer sound simple, I don't know too much on computers, I know I should've got a professional to do it but I didn't have the money.