Can you please explain to me how to change the layout of my product page so that the product image and description is listed first and the BUY button is under this?
On my page I have the price and buy button under the item title and then the picture and description (content) under the buy button.

You can try these options:

1. TCP Look&Feel/Theme Compatibility menu: Assign “Align of buy button in content” to “South“,in section “How to display Single Content”.

2. Try to create your own template for products (a file called “single-tcp_product.php“). Please, take a look to http://codex.wordpress.org/Post_Type_Templates. Then, you could use template functions of TheCartPress: tcp_the_buy_button, tcp_get_the_thumbnail, (http://thecartpress.com/docs/developer-docs/api-template-tags/) etc.

3. Or you can add CSS styles to your theme, to place the different parts of the buy button.