I have an elite book i5 4 gb ram could I upgrade and get nividia or and as my graphics card?

No. Graphics cards are generally built to plug into standard PCIe slots on a standard-format motherboard. Notebooks have highly customized motherboards that only support one or a small group of CPUs and GPUs (if a GPU is present). In most modern cases, the CPU and GPU are soldered on and can't be changed at all.