Hello Trevor Park,
All styling information that is used by the administration part of Sitefinity is located in the /Sitefinity/Admin/Themes/Default
folder under your project. There you can find the modules.css
file containing CSS rules used by modules. The images are located in the Images
subfolder. You can add anything that you need for your module.
There is also the Skins
subfolder which contains styling information about the RadControls used in Sitefinity.
If you want to see what CSS classes are applied to each control, refer to the templates located in /Sitefinity/Admin/ControlTemplates
the Telerik team