thanks for your respond

the LCD is connected with P1 port.
RS with P2.0
EN with P2.1
and the Start switch with P3.0.
also, i need to add another switch for Stop counting and a switch for selection Up/Down counting.
however, i got some samples for how to initialize LCD and display char on it.

now, 1.how to display the counter in minutes:seconds format "00:00"??
2. how i can combine the count up and count down in ASM code?

i am a very beginner in ASM and PIC programming :(

many thanks for your help.