I got good news and bad news...
Good news:
1. The slot circled in RED is a PCI-E slot. It can accept graphics cards. I would assume it is a x8 slot by the look of the hardware in the picture.
Bad News:
1. I made an arrow on the PCI-E slot. I am almost 100% positive it can only accept a "single slot card" Which is just fine...there are many good single slot cards...but it will limit your choices.
2. To run a modern graphics card...the power supply will need to have the power to do so. I again am assuming you will have to buy another power supply also. You'll have to give us the
exact make and model number of your computer then we can figure out your best option