This is by far the easiest example I have found on the net.
http://jonraasch.com/blog/a-simple-jquery-slideshow
Summaring the example, this is what you need to do a slideshow:
HTML:
Position absolute is used to put an each image over the other.
CSS
The image that has the class="active" will appear over the others, the class=active property will change with the following Jquery code.
If you want to go further with slideshows I suggest you to have a look at the link above (to see animated oppacity changes - 2n example) or at other more complex slideshows tutorials.
