Adding picture to site

I want to add a picture to mono of my site. There are already four pictures. It seems like flash but I think its not flash actually. How to insert another image in it and make it appear like others do?

It is not FLASH, simply HTML and Javascript.
If you look at the HTML pages (default.html, product1.html, product2.html, etc.) you will see an obvious BLOCK that defines the pictures.
Editing that (on every page) is the primary task. There is an excellent example to follow within the existing site. Make a copy so you can revert if you make a mistake and you will learn quite a lot. Plus gain an immense sense of satisfaction!

Of course, you need to add the new photo in the “Images” directory.