The Emerald Theme Manager allows you to install, edit and switch between Emerald themes. In order for it to work, select Emerald as your window decorator. You will also need to enable the Window Decorations plugin (via CCSM).
As a window decorator, Emerald controls the appearance of your window borders; please see your desktop environment's own theme settings if you wish to change the appearance of things inside windows, such as buttons, menus and scrollbars.
Importing Themes
To import themes, click on Import... and navigate to the .emerald file you wish to import. There are quite a few nice themes at Compiz-Themes.org.
Alternatively, you can double-click on the files in a file manager, and Emerald will open the Import dialog.
Options
Themes
Select a theme from the list and your window decorations should change immediately (or after reloading Emerald, in some cases). You can edit any theme easily, for instance to change the shadow or title font, but you can also go into more complicated aspects of customization, such as adjusting the colors and opacities, or even replacing the titlebar buttons with your own. With extensive modification, it is possible to make an entirely new theme using the settings under the Edit Themes tab.
Repositories
Follow the instructions in the Repositories tab to fetch more themes from the internet. You may get an "Error calling tar" message a few times, but that seems to be normal as of now.
Emerald Settings
In the Emerald Settings tab, you can change various global Emerald settings, such as the button fading options and titlebar double-click actions.