I think you mean the screws that attach the 'cleat' to the shoe. Try your LBS I'm sure they'll have one laying around. Otherwise you'll have to try and find one online.
If you end up getting a new set of cleats you can just re-use the screws from the previous pair.
You could also check out your local hardware store and see if they've got anything similar.
Nah actually I meant the screws that attach the toe clip to the pedal. I was thinking of trying the hardware store in any event. Thought that being new to cycling there was some other source I was overlooking.