Hello All,
Thanks for all your response. I have managed to crack the solution and now able to connect to the Share Point URL and get the title of the site. I am getting there and my next task is to get the available lists from the site and target one particular list and store/retrieve data.
The solution I used was from the following blog: https://www.c-sharpcorner.com/article/sharepoint-csom-for-net-standard/
Obviously, you would get some errors which you have to resolve one by one. There is a very good explanation in the Microsoft and all you have to do is enter the error code and description.
Some common errors you might expect: Invalid request, Invalid grant, Interaction required
Please, reply me here if you are stuck with any of the above errors and I can help you to fix!
Also, the links @Hui Liu-MSFT suggested are bit outdated (depreciated or will end support in few years) as Microsoft has improved their way of connecting to Share Point.