Please see this article: Where is the Theme Editor tool?

Open the Event Theme tool. The following screen opens ...

There are 3 types of color themes (bullet numbers refer to the numbers in the black dots):

1. Library Themes - these are provided as a place to start - Copy them and modify them to make them your own - once copied, they become the Current Applied Theme
2. My Themes - these themes have been copied from the Library Themes section and modified (or not) - to use one of these for your event, click the Apply button when you mouseover the theme
3. Current Applied Theme - this is the color theme that is currently applied to your event

To begin, select a theme that you like from the Library Themes section and click the Copy button. Doing so will move a copy of it to the Theme Editor tool where you can make your changes in real time.

When you exit the Theme Editor, the theme will automatically be applied to your event.

When you copy a library theme, your registration page will open and a Theme Editor Tool Panel will display in the upper left corner. Click and drag the title bar to relocate the tool panel on the screen.

The theme that you copied will be applied to your event's registration page. You can now make changes to it.

First things first: Name your theme (bullet numbers refer to the numbers in the black dots):

1. Select Theme Name from the menu
2. Provide a name in the field
3. Click the SAVE CHANGES button

The dropdown menu lists all of the page elements that can be changed by this tool.  

Your new theme will be applied to your event when you save your changes and leave the Theme Editor tool.

You can return to the Event Theme at any time and make additional changes or select a different color theme entirely.

IMPORTANT: The color themes you create are saved to your member space so that you can access them from any event.

Please see this article for more detailed information on what can be done with the Theme Editor tool: What can I do with the Theme Editor?

One of the most significant features of the Theme Editor is that you can format your registration web pages in 2 different ways:

1. 100% Width - your event displays at the full width of the browser's window width - How do I use the 100% Width editor?
2. Fixed Width - your event registration pages will display as a fixed width of 740 pixels wide - How do I use the Fixed Width editor?