Need Help Upgrading Desktop, Low Budget

[ZaCookieMonsta1]

I want to get the new next gen games, but I don't think that my desktop can handle them. I know absolutely nothing about computers so I really need help here. Here's the specs for my PC:

Lenovo H415
Microsoft Windows 7 Home Premium
x64
Processor: AMD A4-3420 APU w/ Radeon HD Graphics, 2800 Mhz, 2 cores, 2 logical processors
RAM: 6 GB
SMBIOS Version: 2.6
BIOS version/date: LENOVO DZKT31AUS, 4/9/2012

I just wanted to know what graphics card I should get for my computer. All I want is at least 40 fps on a game like BO3 zombies on medium or low settings. My budget is under $250, and if there's anything else I should upgrade, please let me know. Thanks!

 

[dxleni]

If you have a 250 dollar budget you can easily get a Gtx 960 for about 190 to 200 dollars. It doesn't matter what brand EVGA MSI or Gigabyte