Computer monitor doesnt display?

I recently built a computer from purchasing parts and putting old parts into a brand new tower i got. i bought a micro atx motherboard, new video card, ram, hard drive, ect. I hooked up everything properly and tower turns on, the monitor wont display anything though. I know i properly hooked all wires up right to the motherboard and that my parts are working, i didnt install my video card yet because i was going to run the computer with the onboard video it has already but it doesnt work, i tried puttin vid card in after and still no monitor display. The monitor works fine it displays on other computers ive tried. I heard that the problem might b comming from the motherboard and also heard it might b comming from the bios. Im not the best when it comes to computers, i know alot. but i am clueless at this point. Anyone know the problem as why am i not getting any display??