The blocks in the sidebar(s) on the left and/or right can be managed through the blocks administration interface (administer >> site building >> blocks). You can

• turn blocks on or off.
• configure individual blocks so that users may choose whether to turn them on or off
• change their location to left or right, or move them up or down.
• configure individual blocks to show on specific pages or areas of the site.
• create custom blocks (see the "sample block").

The menu administration interface (adminster >> site building >> menus) will allow you to customize the main navigation menu (the one with your username as a title). You can create new menu items, rearrange existing ones, or even create whole new menus. You can change the order by simply dragging the menu items to their desired location.

Navigation links in the header also can be modified in the menu administration interface. The links in the header are called "Primary links." Some themes use a different theme generation method, so you may need to configure these links by configuring the theme itself through the theme administration interface. Other themes may not provide navigation links in the header at all. You can change the order of primary links by simply dragging the menu items to their desired location.