MyBB Community Forums

I just started with MyBB, it is the first customization project for me. It seems very simple and intuitive, but I am confused about something.

How do I know I am editing the right item without destroying a necessary item.
Here is what I mean:

In the images directory there is the file off.gif for example. If I open the file it is obvious what it is. Simple enough. If I edit it, it get's edited. No problem.
If I want to do this, it does so for the entire forum. How can I edit it for a custom theme. Do I just add a new file to the same directory and change the filename? Do I copy the images directory and rename it? and etc.
There is no way to create a duplicate theme with an images directory?

Anyway, before this post turns stupid, my real question is this -

After a default installation of MyBB. What do I need to do to create a new theme from scratch, and NOT interfere with the default theme. What is the best way to do this. I don't need instructions on how to edit.
Also, how do I save my theme once it is edited. The only thing I found was an xml export import.

Again, someone that has actually and properly created a theme, please explain how you kept it organized, where you saved your images and etc.

I want to make sure I don't break my forum in the process.

This tutorial explains how to do this: http://community.mybb.com/thread-72931.html

For creating a theme, in the Templates & Style tab there is a sub-tab 'Create New Theme'. I'm assuming you already got that far but I just wanted to put it out there just in case. After you've created the theme go into the Template Sets and click on the 'Add Set' tab. I normally name my template set '[Theme Name] Templates' to go with the default convention. Then go back to the 'Themes' tab and in you theme's settings change the template set to the one you just created.

Normally, custom theme images are saved in the 'images' folder by the theme's name. You should put a copy of all default images plus the english and toplinks folder. You can set the theme's folder path in the theme's settings.

I'm not sure what you man by saving the theme. To make any changes you have to save mainly the global.css file and the templates which, by reading your thread, you probably already know of. Though, once created, the theme is already saved into the database so there really isn't a button to save the whole theme.