Broadleaf Commerce Discussion Forums

Hello

I just downloaded Broadleaf 4.0. I have some experience in java programming.
I want to put quantity field in product view, instead of cart view, calculate price using Price Tier and show the result,
so user can write quantity and get instant result of price calculation, that depends of sku and quantity.
Where I should start, where I can looking for relevant classes? What is necessary to get this done?
Whats yours experience in work with product and cart views?

Thanks in advance
Chris

Probably ProductController and the template, product.html.