Hi MikeB
Take a 4.7Kohm resistor from +5v and connect it to the input. Connect a switch between input and ground.
This circuit will count every time there is a transition from high to low voltage on the input pin. The first thing you may notice is that each time you hit the switch and expect an increase of 1 in the displayed count, you get several counts - this is switch bounce and can't be avoided unless you add a debounce circuit first. There are also many other kinds of input that you can use which don't suffer the bounce problem to the same extent, for example, optical or magnetic switches.
Hope this helps
Ed
