You should see a POST, the BIOS will usually look for devices and try to boot the OS. But, your not seeing anything.... Are you sure the screen works? (Laptops are notorious for damaged/non-working screens.) Do you hear any sounds (like fans or DVD disk tray noise, etc...) or see lights turn on and/or stay on?
Before you try to get a POST screen again, unplug all the unnecessary accessories (for instance, unplug any external hard drives, flash drives, mice, keyboards, USB hubs, unplug your internet cord and so forth...); also be sure you have the correct battery for your laptop and that its securely mounted in place and also that the power cord is firmly plugged into the laptop and into a wall outlet you are sure has power.
I have to ask, why isn't there a hard drive? Is there anything you can tell me about this computer that might be worth knowing? Does it have signs of physical damage, do you trust the person you bough it from, has anyone tried to "fix" this problem, etc...?
(Edit: Can I ask how much you paid for this computer?)