Building P.C. )Graphics wont work)

O.K. Well it is my first time building a P.C. and I have run into a problem. I have installed everything and I power on the P.C. and everything works... but when I look at the monitor it says "monitor is working" and wont show anything.

I will post my specs and hopefully I can get some help

I am using:
Asrock 4coredual-vsta motherboard
Pentium Dual Core processor
1GB of DDR 333 RAM (I kno its old but I'm not trying to build a power P.C.)
EVGA e-GeForce 8400 gs, 512mb DDR2 (no OnBoard graphics)
and a Coolmax 500 watt power supply

Now I know that not much of this is very good but again I'm not building a power P.C. I just want a P.C. that works. I've looked everywhere for a solution but I can't find one. If you could help I would greatly appreciate it. Thank You