Binary game program

Hi,

I want to make a program, which asks the user to enter the number of binary digits and the lenght of time for which the binary number should be displayed on the full screen. (eg. if the user enters 4 no. of binary digits and length of time as 10 sec, then the screen should display 1100, 1001, etc -- ie the number should be random but only of 4 digits, for 10 sec )
So, can anyone pls help me on this.

Hoping for your kind co-operation and thanks in advance.