Hi,
Well for start, site looks to busy for me with that many categories and 2 columns.
I would definitly go with one column theme and reduce the number of categories displayed on main screen. I would put subcategories inside each category for better navigation.
About the colors, blue and green are good complementary colors, but this is too much, it looks more like site for children.
Use more gray in your green so it's more neutral.
I also see you used icons from many different sources and their style doesn't match.
For example, you are also repeating one icon for the whole category, so there is 4-5 same icons, and category below/up/right/left has every icon different.
Well to put it short, there is too much confusion in your site, very unpleasant for the eyes.