jquery uses animate to turn the picture around

HTML section

<div class= "bag3 Panel" >
<div class= "Bg3_content" >
<div class= "Bg3_img" >
<div class= "First2" >
<div class= "Img_top" >
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>

</div>
<div class= "Img_middle" >
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>

</div>
<div class= "Img_bottom" >
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
</div>
</div>
<div class= "Second2" >
<div class= "Img_top" >
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>

</div>
<div class= "Img_middle" >
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>

</div>
<div class= "Img_bottom" >
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
</div>
</div>
</div>

</div>
<div class= "Next_left" ></div>
<div class= "Next_right" ></div>
<div class= "Next1" ><div><a>|</a></div></div>
</div>

CSS Section

. bg3_content{
    height:385px;
    width:60%;
    Position:absolute;
    left:310px;
    bottom:148px;
   Overflow:hidden;
}

. bg3_img{
    width:2400px;
    height:100%;
    Position:absolute;
    left:0;
    top:0;
    Font-weight:bold; " >purple;

}
. first2,.second2{
     width:900px;
    height:100%;
   Position:absolute;
}
. first2{
    Position:absolute;
    top:0px;
    left:0px;
}
. second2{
    Position:absolute;
    top:0px;
    left:900px;
}

/* Fourth screen left/right toggle */
var num=1
$ (". Next_left"). Click (function () {
Alert (NUM)
if (num==1) {
$ (". Second2"). CSS ("left", " -900px");
$ (". First2"). Animate ({left: "900px"},500,function () {
num++;

});
$ (". Second2"). Animate ({left: "0px"},500,function () {

$ (". First2"). CSS ("MarginLeft", "900px");
});
} if (num==2) {
$ (". First2"). CSS ("left", " -900px");
$ (". Second2"). Animate ({left: "900px"},500,function () {
Num=1
$ (". Second2"). CSS ("left", "900px");
});
$ (". First2"). Animate ({left: "0px"},500,function () {


});
}

});
$ (". Next_right"). Click (function () {
Alert (NUM)
if (num==1) {
$ (". First2"). Animate ({left: " -900px"},500,function () {
num++;
$ (". First2"). CSS ("left", "900px");
});
$ (". Second2"). Animate ({left: "0px"},500,function () {

$ (". First2"). CSS ("MarginLeft", "900px");
});
} if (num==2) {

$ (". Second2"). Animate ({left: " -900px"},500,function () {
Num=1
$ (". Second2"). CSS ("left", "900px");
});
$ (". First2"). Animate ({left: "0px"},500,function () {


});
}


});

jquery uses animate to turn the picture around