1. First you must sign into your gmail account, please see other notes if you dont have an account. Afterwards find your website and you will see a tool bar like this in google sites and then click on the 'more' drop down button and select "edit site layout'.
2.Next move your mouse over the Navigation box, click on the "edit" link.
3. Once the "Configure Navigation" window opens, check the box next to the phrase "Automatically Organize MyNavagation" in order to have your sidebar automatically organized after the creation of a new subpage, or leave it blank if you do not wish for this to occur.
4. Within the same window you can also chose the level of pages shown, as well as manually change the order of the items in your sidebar. The latter is done by leaving the "Automatically Organize My Navagation" check box clear, then a box will appear underneath that will display all the items in your sidebar. To change the order of an item in your sidebar, highlight a specific title on the sidebar and use the arrows to the right to move the title in the direction desired. Repeat this as necessary with each item on the sidebar until the desired order is achieved.