You can select themes to change website colors, backgrounds, and page headers. Custom pages and menus are also possible.
Use your website menu "Administration", "Administrators Only", "Manage Organization Profile". On this page you will be able to select a "theme" that changes the overall set of colors used on your website.
On that same page you can upload or select an image to appear at the top of each webpage.
There are several other options you can explore on the "Manage Organization Profile" page, including selecting a background tile to be used on all pages.
To format your Home page and your Membership Information page, use your website menu "Administration", "Manage Web and Email Content". Select the page to be altered and use the editor to create and format your page.
If you have a Premium Subscription you can further customize your website. Use the menu "Administration", "Manage Menus and Custom Pages". Here you can add, remove, or rename menus. You can create your own pages and reference them with new menu items.