Slideshow using Jquery, images do not fit window

I am trying to make a slideshow using jquery, I am a rooky in this code and am only familiar with css and html (though I am unsure how to position things in css). I want to create my slideshow and followed this template however I don't know how to change aspects of it, I tried messing around with it however no luck. My images are much bigger than the slide window created, I want to fit the image to the window, since now only a portion of the image is shown, which doesn't look very good.

So I was wondering how I could fit the complete image in that slidewindow (not a portion)

Here is what I have as html:

<div id="slideshow">
<div id="slideshowWindow">
    <div class="slide">
        <img src="Images/DSC_0419 copy.JPG" />
    </div>
    <div class="slide">
        <img src="Images/DSC_1019 copy.JPG" />
    </div>
    <div class="slide">
        <img src="Images/DSC_2975.JPG" />
    </div>
</div>
</div>

My CSS:

#slideshow #slideshowWindow {
width:1000px;
height:700px;
margin:0;
padding:0;
position:relative;
overflow:hidden;

}

#slideshow #slideshowWindow .slide {
margin:0;
padding:0;
width:1000px; 
height:700px;
float:left;
position:relative;

}

And this is my Jquery script:

<script type="text/javascript">
$(document).ready(function() {

    var currentPosition = 0;
    var slideWidth = 1000;
    var slides = $('.slide');
    var numberOfSlides = slides.length;
    var slideShowInterval;
    var speed = 3000;

    slideShowInterval = setInterval(changePosition, speed);
    slides.wrapAll('<div id="slidesHolder"></div>')
    slides.css({ 'float' : 'left' });
    $('#slidesHolder').css('width', slideWidth * numberOfSlides);   
    function changePosition() {
        if(currentPosition == numberOfSlides - 1) {
            currentPosition = 0;
        } else {
            currentPosition++;
        }
        moveSlide();
    }
    function moveSlide() {
            $('#slidesHolder')
              .animate({'marginLeft' : slideWidth*(-currentPosition)});
    }
});
</script>