HTML - How can I create an increment/decrement textbox on an HTML page?

Simple :)

HTML :

<div id="incdec">
    <input type="text" value="0" />
    <img src="up_arrow.jpeg" id="up" />
    <img src="down_arrow.jpeg" id="down" />
</div>

Javascript(jQuery) :

$(document).ready(function(){
    $("#up").on('click',function(){
        $("#incdec input").val(parseInt($("#incdec input").val())+1);
    });

    $("#down").on('click',function(){
        $("#incdec input").val(parseInt($("#incdec input").val())-1);
    });

});

did you try input type="number"?