I'm sorry op, but this isn't a computer, is a loving toaster inside of case. There is absolutely positively no way you're going to upgrade or install a graphics card on this computer. If you try to upgrade it all you're going to find yourself in is a hassle so much to the point that it's actually more beneficial to build your own computer.
Like the others said sell this to some smuck online and use that money to get yourself some parts and build a pc that meets your needs and doesn't have a layout and parts that are stuff.