Computer help! Please...

[Lexun]

So just like many Americans around this time of year I have come into some money from our dear government....

In light of that I want to upgrade my computer to improve it in anyway I can in the most minimal way. The computer is pretty old and the parts are defiantly outdated but hoping maybe a part or two can be changed to help it come into the new age. I also understand that i might have to scrap it completely but holding on to hope!

The following is what my computer has on it im not super computer savvy so i just need advice on what i can do. If im missing something important let me know!

System Manufacturer MSI
System Model MS-7599
System Type x64-based PC
Processor AMD Phenom(tm) II X4 970 Processor, 3500 Mhz, 4 Core(s), 4 Logical Processor(s)
BaseBoard Manufacturer MSI
Installed Physical Memory (RAM) 16.0 GB
Available Physical Memory 12.9 GB
Total Virtual Memory 32.0 GB
Available Virtual Memory 28.7 GB
Name AMD Radeon HD 6900 Series
Resolution 1600 x 900 x 60 hertz
Bits/Pixel 32


I can currently play the game only on the Standard Desktop Settings and sometimes it struggles in populated times.