How do I go about creating my own styles?

The easiest way is to find a preset style with one or more elements that you will want in your new style (e.g. if you will want a piano, start with the Acoustic Piano preset style). Then press the NEW key and change the style to your liking. Don't worry - you cannot mess up any of the preset styles! Once you are happy with your new style, save it and give it a recognisable name.