That blue in main menu is too aggressive.
Who cares about the colors except for those prissy designers!
Do NOT be tempted to add a page background. Your pages load too slow as it is. Any more content and it will grind to a halt.
Cut the crap, keep it simple and get the message across.
Fast transitions on banners are a distraction. Most visitors are capable of clicking on a dot to see the next slide.
By making the main text too big its actually harder to read.
Unless you are going to build a completely separate mobile version of your site, use a responsive template.
still search any good book about making website responsible..
I think prestashop is best ecommerce, but its hard to learn the code, especially for a begginer like me, i currently using opencart coz personally the code is easier to understand for me..to read what all else wrote..
but i would recommend you google best eCommerce sites of 2012 and go from there.
to be blunt: your current design is not good. from the hood (code) to the body.
Potential certainly exists though! Good luck dude