Hallo Hammad,

beside to the good hints of Mahmood, I would recommend you to have a look at 'instruction set' of a common 8XC51 microcontroller. Then you will see, what such a micro can do at all.
Most of the time some data is transmitted between different memory locations, e.g. from micro to LCD, or from accumulator to data memory, etc. Or data has to be modified, e.g. shifted in accumulator, for achieving some calculation, etc.
The magic of microcontroller is, that most difficult and sophisticated calculations and manipulations can be done by using only these extremely simple and easy instructions, which can be found in instruction set!! But sometimes an enormous number of such instructions are needed...

Start with very simple things!! And read, read, read, read, read, read, and read...

BTW: You will find extremely useful information, when having a look at 'Tutorials' and 'FAQs' on the left side, or when just making a search in archived messages.

And if you are posting clear formulated questions here (after intensively 'googling'), you will get an universe of help...

Good luck,
Kai