PC hardware--CPU & Motherboard & RAM/GPU
I am building a computer for the first time, I know a good bit about computers but i have a question about the GPU. I know that I obviously need a CPU unit, but with the GPU do i need a separate GPU unit or can I use a video card that has GPU on it? Such as this one.
You cannot buy a "separate GPU" (no need to add "unit" - that's what the U is for (Graphics Processing Unit or Central Processing Unit)) - they will either come as part of a graphics adapter (like the one you've linked to, which carries a GeForce GPU), or as part of the motherboard's northbridge (as an "IGP") or built into the CPU (these combined chips may be marketed as APUs). In general stand-alone video cards offer the best performance, however integrated models tend to cost substantially less and use less power. Depending on your needs from the computer, a dedicated graphics adapter may or may not be worthwhile. Generally if you are intending the computer to play videogames or do other graphics-intensive tasks, a dedicated adapter is the best choice. However if your usage is to browse the web, watch movies, and so on - an integrated adapter will be suitable (and modern integrated adapters tend can handle a number of games - an example would be the new AMD 7850k). The quick answer to "what you should buy" really depends on what you want/need the computer to do (and of course your budget); looking at the published system requirements for the various software you need to run can be very helpful, especially for a first-time build.
As an aside, regarding that model graphics card specifically, I would advise you not to purchase it. The 4GB frame buffer is of no benefit to performance, despite costing considerably more. The 2GB model is a better choice. Here's a performance comparison of the two: http://alienbabeltech.com/main/gtx-770-4gb-vs-2gb-tested/3/
If you have any further questions regarding specifications or how-to's with the build, or need clarification, feel free to ask.