Hover-over pictures in a wp template site

want a simple code to add to the post

[Indo]

I use a template from wp Studiopress.com to make my weblog. I like to add on the "Home" page pictures about 8 below each other showing "before" and when hover-over a picture "after" shows up.
To be clear first the wrong one and then the right one.

I know how to open the firebug, but I have nearly no experience with html and/or ccs coding.
I found via google several hover-over code, but where do I have to insert that in the wp code?
Any advise is very much appreciated.

[edited by: lorax at 5:56 pm (utc) on Jul 23, 2012]
[edit reason] removed site link [/edit]

[lorax]

Welcome to WebmasterWorld Indo.
Unfortunately, the answer to your question has many possible answers. Without experience our answers aren't likely to mean much or do you much good as you will likely need to edit one of more of the theme's files. Have you posed this question at the StudioPress forum? They may have a simple answer that doesn't involve a lot of code editing.