keypad operation with avr for traffic signal controller project

dear all,
i am working on traffic light controller using atmega32.
i am not getting the logic behind keypad.
actually in traffic controller we have to enter the date, time, signal working time, slot time, red time, green time, yellow time and many more entries.
at starting we get a message ''press any key'' at LCD.
know we will press any key from the 4x4 keypad.
then we will go to desired entry by using the specified path.
i just want to know that let our signal is working and road 1 is green for 30 sec.
counter is counting 30 seconds. at the same time i press any key then at same time without any delay it will reach to that place
for which i press the key.
i want to know that how it will reach immediately at same place.

earlier i worked on rgb led controller,
i used there 3 keys for changing the color, intensity of light, speed of changing of color,
i used there some while loops after each short time interval let 100ms. so here i have to wait to complete that perticular step & its time then it will detect the key press.
i didn't get it immediately after my each press.
so please provide me solution for this keypad problem
thanks