Your site's menu is easy to manage and maintain.
You can add more content, order content, create drop down lists, edit names, links to external sites and much more.
Classic mode Left hand menu: Appearance >> Menus
You can simply drag and drop you list to create the order that you want.
You can use the custom links to create links to specific areas in your site or even on other sites. Just give it a name and a link and click add.
When creating drop down menu's you have to use a custom link as a parent that has a url value of #. This will result in a parent that whilst clickable won't change the page you are viewing, but will activate the dropdown list function to show the child items
You can then drag your chid item to indent under your parent item.
Obviously your theme must support drop down menus and the option should be enabled for it to work.