Hi Mooders,
At iMoot 2015 I presented on theme customisation for beginners, that video has just been released by Pukunui (A Moodle Partner). You can view the whole presentation here:
And get the slides from: http://www.slideshare.net/gb2048/theme-customisation-for-beginners
If you find this post useful, please mark it so.
Cheers,
Gareth