This page contains key points with respect to Report Structure in Google Analytics

In the left hand navigation, you will see that your reports are organized into categories:

1. Visitors,
2. Traffic Sources,
3. Content,
4. Goals, and
5. Ecommerce.

If you do not have an ecommerce site or don’t have ecommerce reporting enabled, you will not see the ecommerce section in your navigation.
To view reports, click on any of the categories and the reports available within that category will appear. Some reports contain additional sub-reports, like the AdWords report under Traffic Sources. Click the arrow to see the sub-reports.

To change your date range, click the arrow next to the active date range displayed at the upper right of all reports. You can then use the Calendar or the Timeline to select a new date range.
The Calendar tab allows you to select date ranges by clicking on the day and month within the calendar or you can type dates in the Date Range boxes. The Timeline tab has a date slider that you can resize and move to cover any range of dates. You can see your the traffic of your site trends in the Timeline.

You can select a date range to compare to the current selected date range. When using the Timeline to set a comparison date range, you will see two date sliders instead of just one.
You can use a comparison date range to see how your site is performing month over month, year over year or even from one day to another. The date range and comparison date ranges you select will apply to all your reports and graphs.

Most reports include an over-time graph at the top. You can make this graph display data by a) day, b) week, or c) month.

You can also compare two metrics on the same graph to see how they are correlated. Click the arrow in the top left of the graph.
Then, click the Compare Two Metrics link and select which two metrics you want to compare. In this example, we are graphing 1) visitors versus 2) average time on site.

You can roll your mouse over the graph and see actual numbers.