i want to learn about and gain experience of 2G/3G/4G/5G,can anyone help

Great question. However, it is necessary to know more context. e.g. Are you a technical expert from another domain or are you a non-technical person? Why do you want to learn? Is it just to improve your knowledge of mobile technologies or to apply for a role? I could respond more concretely if I had such insights first. Generally, 2G/3G are old technologies and generally, 4G is dominant today with significant growth of 5G now. So, it would be useful to focus your learning on 5G right now. Within 5G, we have multiple network requirements and technologies. While a high-level end-to-end view is possible (e.g. for a network solution architect), every area like 5G Radio, Core, Transport, Routers, Optics, FWA, software, applications, and services are all big areas to learn and grow. There is a lot of high-level training available for free (and paid) on the web too. You could also find some latest highlights in different 5G domains on the Nokia website and our 5G certification program here: https://www.nokia.com/networks/training/5g/bell-labs. Once you are more specific, I can provide more details. Hope this is useful. Wishing you success.