How do i turn on another video card on Asus M4A89GTD PRO motherboard ?

I have ASUS m4a89GTD PRO motherboard that comes with an integrated video card. i bought sapphire 5750, but the system wouldnt find it.. i tried a lot of things, but it wouldnt go. I even went as far as turning the onboard card off, so now i cant even turn my monitor on. And thats a problem. I would be more than happy if someone can give me a solution. Thanks|||Normally, you would just plug your monitor in to the corresponding spot on the graphics card, then it would work....... then you'd probably want to install your drivers.