Add products, shopping cart to my site www.thesurfyogi.com

I have designed a website called www.thesurfyogi.com. Under my header in the menu section I have 4 categories that I want people to be able to click in to buy products. These are; 'surf gear' 'yoga gear' 'ebooks' 'videos' I have about 15 products to sell that need to be placed within these menus. Some products have different sizes therefore need a size choice when purchasing. I have all the photos and information on the products in a word document. You will need to use your IT skills to make this look professional on my site. The store needs to stay with the current theme of my site with photos and colours. I need the shopping cart installed and linked to my paypal account. I DO NOT WANT MY CURRENT THEME ALTERED, I ONLY WANT WHAT IS REQUESTED ABOVE, therefore please do not email me regarding an overhaul of my site, this is not what I am requesting. If you think you can do this gig, please give me examples of how you will do it and what it will look like. thankyou