well, drag a label, and your two buttons onto your page with the drag and drop ui
name the label: placeholderLabel, set the default value to a zero or whatever you want
name the plus button: plusButton
name the subtract button: subtractButton
on each button, add an event (on a click) and then select the run javascript action
javascript code for both buttons:
code
var label = Appery('placeholderLabel');//label object
var newValue = Number(label.val());//gets what is currently in the label and converts it to a number
// put newValue++; or newValue--; here depending on which button you put this code in for
label.val(newValue);//sets the label text
/code
that should do it, hope this helps!