First time builder, Need help!?

Did you turn on the switch on the back of the PSU? Everything on the front of the tower, power on, reset on, usb ports, headphone and mike jacks, etc are connected by all those little single wires to the motherboard. You have to be a little careful when hooking them up. My tower and motherboard instructions could have been a tad clearer. It was my first build. Only thing to do is to double check everything. PSU connections, re-seat the ram and graphic card, if not on-board, hard drive and DVD connections, etc. Then go from there. Then I guess you would have to consider some DOA hardware possibility. Hope this helps. Good Luck.