ผมจะเขียนเกี่ยวกับวันที่ผมจะทำยังงัยครับ ช่วยนิดครับ

<script type='text/javascript'>
var calendar={
   dateTime:new Date(),
   start:1,
   end:1,
   max:0,
   topic:"<div class='topic'>Sun</div><div class='topic'>Mon</div><div class='topic'>Tue</div><div class='topic'>Wed</div><div class='topic'>Thu</div><div class='topic'>Fri</div><div class='topic'>Sat</div>",
	make:function(){
	  num=this.max*7;
	  var d=document.getElementById('calendar');
	  for(i=0;i<num;i++){
		  clss =i%7;
		  if(this.start>i || this.end<i-this.start+1)
			d.innerHTML+="<div class=d"+clss+" >&nbsp;</div>";
		  else
			d.innerHTML+="<div class=d"+clss+" >"+(i-this.start+1)+"</div>";
	  }
	   var listmonth =new Array("มกราคม","กุมภาพันธ์","มีนาคม","เมษายน","พฤษภาคม","มิถุนายน","กรกฎาคม","สิงหาคม","กันยายน","ตุลาคม","พฤศจิกายน","ธันวาคม");
	   document.getElementById('sel_m').innerHTML=listmonth[this.dateTime.getMonth()]+" "+(this.dateTime.getFullYear()+543);
	},
	set:function(){
		daysOfMonth =new Array(31,28,31,30,31,30,31,31,30,31,30,31);
		year =this.dateTime.getFullYear();
		div4 =year%4;
		div100=year%100 ;
		div400 =year%400;
		 if((div4==0 || div100==0) && div400!=0 ){
			daysOfMonth[1]=29;
		}

	  this.dateTime.setFullYear(this.dateTime.getFullYear(),this.dateTime.getMonth(),1);
	  day=this.dateTime.getDay();
	  this.start=day;
	  this.end=daysOfMonth[parseInt(this.dateTime.getMonth())];
		
	  this.max=parseInt((day+this.end)/7)
	  this.max+=((day+this.end)%7 != 0)?1:0;

	    var d=document.getElementById('calendar');
		d.innerHTML=this.topic;
		this.make();
	},
	prev:function(){
	 this.dateTime.setMonth(this.dateTime.getMonth()-1);
	 this.set();
	},
	next:function(){
	this.dateTime.setMonth(this.dateTime.getMonth()+1);
	 this.set();
	
	}
	
	
}
window.onload=function(){
calendar.set();
}
</script>
<style type='text/css'>
#calendar div{
text-align:center;
 float:left;
 padding:4px;
 width:30px;
 border:solid 1px black;
}
#calendar .d0{
 clear:both;
 background:red;
}
#sel_calendar{
text-align:center;
 width:280px;

}
#calendar .topic{
background:green;
}
.clear{clear:both};
</style>
<div id='calendar'></div>
<div class='clear'></div>
<div id='sel_calendar'>
<input type='button' onclick='calendar.prev()' value='<'>
<span id='sel_m'></span>
<input type='button' onclick='calendar.next()' value='>'>
</div>