That would be entirely up to you to put on your own Web site pages however you wish, since E-junkie doesn't build a complete online storefront site for you nor impose any page templates on you.
Once you set up your products in E-junkie Seller Admin, we provide you with ready-made HTML codes for your cart buttons, so you would simply copy the codes from us and paste them into the HTML source of your own Web site pages, wherever you want our buttons to appear among your own layout, text and images, along with whatever other custom features you choose to put in your site, such as embedding an mp3 player for sample clips.