To have the "Search" module exactly as the one on demo page, please follow the instructions below:

1. Go to "Extensions" > "Module Manager" and click "Search" module. 
2. Find "Parameters" on the top right and for "Search button" choose "Yes", "Search button as image" choose "Yes".
3. Go to the template /images folder and find "searchButton.gif". Go to "Site">"Media Manager" and upload this image file to the /M_images folder.