Saying that, the reviewer knows what’s what, so if I were you, I’d listen to his advice.
Spend some time on ThemeForest checking out the quality of the templates design-wise to get some idea of what is acceptable. Then Google tutorials on how to design web pages with Photoshop (or GIMP if you can’t afford Photoshop). Practise. And then practise some more until you are capable of creating quality designs. Learn the basics of good design (typography, the Golden Section, the Rule of Thirds, usability, accessibility, etc) too because you could be a whizz in Photoshop and still not know the basics of creating a good design.
Failing that, buddy up with a good designer to concentrate on the design side of things while you work on the code side of things.