The second section of that Flash help page explains how to add the necessary part of your View Cart code to your page that would operate the overlay-style cart in your page. The cart itself is HTML/CSS/JavaScript based, so it actually runs in the HTML layer of the page where your Flash is embedded, rather than being a Flash-based cart itself.
To get functional buttons in Flash that would display the cart and add items to the cart, you would need to extract the href= URLs from the cart button codes you obtain in your E-junkie Seller Admin, so you can program those URLs into the ActionScript controlling your Flash interface.
Any experienced Flash programmer should know how to accomplish this based on the examples provided on our Flash help page, but explaining how to write ActionScript is a matter of general-purpose Flash programming skills beyond the scope of support we can provide.