Windows 7 is Windows
If you have ever used any previous versions of Windows at all (98, XP, Vista, etc...), it's best to think of Windows 7 as being the same as that... with a slightly different look. Windows is what it is, an operating system. Although new features and different layouts are changed/modified with every new release of a Windows operating system, the core remains the same. So, say for example that you are making the jump from XP to 7. You still have the control panel, run command, start menu, and so forth. That's a good place to start. Basically, Windows 7 and Windows XP are the same thing. Windows 7 just has a more modern looking interface and sports a few more features.
Some of the options, menus, and other items have different names. But, they are still very similar. For example, Windows XP has "My Computer." The Windows 7 equivalent to this is simply "Computer."
Windows 7 does have some new features that obviously have no previous equivalent. To learn about these, simply click the Start Menu, hover over Getting Started, and select Discover Windows 7. This should launch a new browser window with the Microsoft website. On this page, you can watch several video tutorials that will teach you some of the basics of Windows 7 in more detail.