This is a question that depends on what you're after exactly with your theme. Powering all of our themes is our WooFramework, this makes it possible for us to include a lot of customizable options in each theme. Meaning you don't necessarily have to touch code to customize your theme. Things like the ability to upload your own custom logo and or background to your theme, choose the typography from Google's webfonts, and many other options included in each theme.
If you're looking for the theme with the most options, we'd highly recommend checking out Canvas as this is by far our most customizable theme within the theme settings.
Outside of our theme settings, you are going to need a basic understanding of HTML & CSS to start customizing the layout and style of your theme. To dig deeper PHP knowledge, specifically to WordPress, will help as well. The WordPress Codex is a great place to start learning.
Finally, when you are ready to customize one of our themes, a child theme is the best approach to take. A child theme will be a place to house your customizations and modifications to it's parent. You'll be amazed at what you can do with a child themes, a basic style.css, and a functions.php file. Here's our tutorial on child themes. There are many resources out there for creating child themes as well, it only takes a quick search!
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