Okay so I have an HP - Pavilion Desktop and when I play games like DayZ I kinda lag. I was wondering if I can upgrade my PC like a new graphics card or more ram and ETC.. I don't know that much about PCs and I wanted to know if I can upgrade the parts of it and if I can what should I upgrade on it for it can run games like DayZ with like 50-30 fps?

This is a link to best buy where I bought it.---
HP Pavilion Desktop Intel Core i3 Processor 6GB Memory p7-1110 - Best Buy