how to trace the register values in a program using keil debug session
Go get yourself a couple of books (text books, data manuals, asm subroutines, etc), on the topic area(s) that interest you and read them cover to cover. Studying takes time and effort, finding the information you need is part of the process. It's not about sitting in front of a teacher/lecturer or expecting to get a memory implant from a third party.
Where do you start? Start with foundational information, start with material that given you an overview of how things function and interact. Microprocessors, assemblers, compilers, linkers, and loaders carry some pretty general concepts in computer science, it doesn't have to be 8051 specific to be useful or relevant.
With a broad understanding of the processes involved you can focus in on specifics.
It's not about rote learning of facts, but the mechanics and application of ideas and concepts.