MAX7219 8 Digits 7 Segements

one more question
I have a 8-digit 7 segment display MAX7219.
now I came across this against a stopwatch, sketch works, but they use there Pin 38, UNO32 's board.
My question is the sketch to fit for arduino UNO??which pin should I use???
This is the project
chipKIT Project 5: Digital stopwatch on seven segment LED display | Embedded Lab, with sketch.

Take your pick. I'd suggest you avoid using pins 0 or 1 but any other would do the trick. You'll have to modify the code accordingly.

In the sketch there is this comment

Start/Stop tact switch is connected to INT0 (Pin 38) pin.

then later on this line of code

attachInterrupt(0, Button_Pressed, FALLING);

So, the sketch uses interrupt 0. On a normal Uno interrupt 0 is in pin 2 so i seems logical that this is the pin that should be used.

See Interrupts for details

Note that these variables

long previousMillis = 0;
long interval = 100;

would be better declared as unsigned longs to avoid problems with rollover to negative numbers that is alluded to on the chipKIT page.