to begin using eCart, you foirst create the cart object.
This creates the file in the WA_eCart folder, in your case the ecart1_PHP.php file. this file does not contain any design, it only contains code.
The next step is to create a new page with the add to cart buttons.
You can create a page from your template, then add the add to cart button behavior to it.
next create the cart display page, the cart display page will show the Cart is Empty text until you use the add to cart page to add an item to the cart.
see the eCart getting started guide.