These are examples of the use of two separate images to create a visual effect when the mouse is over the first image. The images were created in Photoshop CS using the layers palette.
The second image is swapped out for the first using a java script: onMouseOver="MM_swapImage('info','','rollovers/first_imagename.jpg',1)"><image src="rollovers/second_imagename.jpg>
As buttons there is usually a link also attached to the image using "href="webpagename.html".
Each of these images were created in photoshop CS using the Styles palette. In Dreamweaver the "Insert ->Image Object -> Rollover Image" was used to create the rollover.
A navigation bar : This is a horizontal navigation bar inserted with Dreamweaver's "Insert -> image object -> Navigation Bar". The button images were created in Photoshop.