lunoxiscool
Do you mean the theme or the Forms and Fields? If you mean the Forms and Fields you can add Custom Forms and Custom Fields under Admin Panel > Manage > Forms.
If you mean the theme we don’t have any documentation on how to customize the code. The code is open source however giving you the freedom to customize to your liking. The code is also hosted on GitHub where they have a good file manager, robust search feature, and even really nice class/code trees. You are always on your own when customizing the codebase so good luck!
References:
Cheers.
