If this is accurate to your system (you should check the label on your PSU to see if it matches)
This power supply doesn't have any PCIe 6-pin power connectors for video card expansion
That leaves you with 3 options-
New PSU - probably a good idea if you can afford it, that PSU looks pretty awful.
Change graphics card selection to a HD7750 (best graphics card that doesn't use an additional connector)
Use a 4pin molex adaptor like this - http://virtuapin.net/images/adapter-2x-molex-6pin.jpg
Most graphics cards come with them. Not ideal, but it should do the job.