Dear Waqar,

I think for a start you selected a project that calls for all involved things if you are doing them for the first time. A simple digital clock to display HH:MM:SS and with some decent accuracy will demand the following when done with a MCU like 8051 :

1. Establishing an Auto reload timer.
2. Interrupts to recognize the timer overflow.
3. Counter within the Interrupt Service routine to count the number of interrupts to get higher time delay flags.
4. A basic but good understanding of HEX to BCD and BCD to HEX conversion.
5. Driving the display device - and here it is a whole project by itself - the choice to whether to go in for multiplexed displays (more software ) or latched displays (more hardware ) has to be decided first.

Assuming you get past all the above, then your clock will need two modes - a setting mode and a running mode. ANd a battery back up to take care of power shutdown...

Sorry if it looks like I am scaring you. But believe me, starting with a small code to first understand basic I/O operations like most memebers advised, is the way to go.

And if timers tutorial in 8052.com are not clear, please sleep over it and read it again TILL you get it clear. I have not come across in the net any more better tutorials.

Good luck

Raghu