Pictures
How to embed a slideshow of pictures -
Create a picassa web album - click on More - Picassa (you do not need to download Picassa to your computer)
Import pictures to your Picassa web album. Give the collection of photos a title.
Return to your Google site.
Click "Create New" - choose Web Page, give it a title, click "Create"
You will be taken to your new page. Click "Insert - Picasa Slidesh" - choose your web album.