i have a website like:http://www.terranartworks.com/testsite/tsv1/islerimiz.html

i want to change the sources of images,which stays on the white panel,at every click of the grey buttons at the bottom.i did this with switch case but it does this only one click.another clicks they don't.i want to identify only one image tag and change the source according to button.i mean only the xxx part will change according to index comes from button:imajlar/ISLERGORSELLER/xxx/xxx-bilgiler.png

i don't know can i explain my problem.how can i do this?