First: You seem to have started the After Effects render engine, not the main After Effects application. Try starting the main After Effects application, not the render engine application.
Second: You seem to have misunderstood the message about CUDA. That message just says that a single feature (which is obsolete) depends on specific software and hardware---CUDA and a specific kind of Nvidia GPU.
What GPU do you have? If you installed CUDA on a non-Nvidia GPU, it can cause severe problems.
Thank you so very much for your advice!! I'm sorry for the late response.
(It didn't let me login yesterday so I couldn't reply to you immediately)
Based on your advice I was able to find the solution:
Finally I was able to find the main After Effects in my application file and it works perfectly - YAY!!
Thank you again for helping a crazy beginner like me
Thank you, thank you so very much for your wonderful support!!!