The Graphics Card or Video Card as it allows your Computer to display thousands of coloring images on your monitor. Some motherboard have a built-in graphics card in their chipset this are normally low display card which even use your RAM for displaying images but today some high-end chipset motherboard comes with a built-in 3d Graphic card chip which use only enough memory from the system to run. The common reason for installing a graphics card upgrade in your system allows users to run high-end games faster and more smoothly or to add TV/DVI out to your system.
Steps how to Install a Graphics Card
Shut down your PC and switch it off from the main switch. Unscrew the sides of the chassis and carefully side off both the panels and wear an anti-static wristband whenever working with sensitive electrical devices and use both the hand while installing some parts of hardware. If you are replacing the old graphic card you have to unscrew the card fixed to the back panel and carefully slide the card out of the slot and check whether the card has a clip fixed to it depending on the motherboard.
Otherwise, if you do not have any card being installed in your motherboard then check your motherboard supports the AGP or PCI-Express graphic cards. The AGP card represent with color brown and the PCI-Express slots represent with black color and then you can purchase the card according to your compatible ports. Get the new card out from its anti-static bag and carefully push the card into the slots very firmly and tighten the clip if provided by the motherboard to hold the card and also the screw the card on back plate of the panel and check the card whether its moving or not and connect the power cable for the fan on the GPU of the graphic card and whether the fan is clear from the obstruction of floating cables.
At last, check whether or not your new card requires an additional power source. Very few powerful PCI-E cards have a square four-pin power connector slot, so you may need to purchase an additional cable to convert a molex connector if one hasn't been bundled with your graphics card.
And at last slide on both the panels of the chassis and screw it properly and connect all the cables to the machine. And boot up your system and make sure that the POST and windows splash screens are being displayed or not these indicates that your card is installed correctly

Finally, replace the sides of your case and reconnect the cable to your machine.
Boot up your PC and make sure that the POST and Windows splash screens are displayed. This indicates that your card is installed and functioning correctly. If you don’t see any display shutdown your Pc and recheck the card connectors these may be due to while moving the case it must have loosen the cables or power connectors.
And if you see the windows screen you may now install the drivers of the graphic card provided to you by a mean of CD and install your driver and other extra tweaking utilities provided to you on the CD.
After installation of drivers and utilities the system will ask for the option whether to reboot the system now or later and you have to click on now and system will get rebooted you should now be able to reset your desktop resolution by going to the desktop, right clicking, selecting properties and then heading to the Settings tab. You should also visit the manufacturer's website and check for newer drivers, as these will offer optimum performance and iron out glitches with previous driver versions.