In Gnome, the top and bottom menu bars together perform functions equivalent to the Windows taskbar. The top bar contains menus for launching applications, navigation, and system configuration, while the bottom bar keeps track of currently running programs.
In addition, the left end of the bottom bar includes a button to hide all currently opened windows, while on the right are squares that represent "virtual workspaces." Gnome allows you to open two or more workspaces, each of which acts as a separate desktop, just as if you were working on multiple monitors. Clicking on the menu-bar squares lets you jump from one workspace to the next. You will also find the Trash icon on the right.
Navigating menus and windows follows customary conventions. The left mouse button selects items, and double-clicking opens or launches an item. The right mouse button brings up a contextual menu. A number of global keyboard shortcuts are available, too, including Alt-Tab to switch between windows, Alt-F1 to bring up the Applications menu, and F1 for Help.
Working With Applications
The great thing about Linux distributions such as Ubuntu is that they include not only the OS but also a whole bundle of practical, full-featured applications. In Ubuntu, you can access them from the Applications menu, next to the logo in the top-left corner of the screen. Among the default applications you'll find on your Ubuntu system (along with many other free tools, games, and utilities) are:
If those aren't enough for you, you can always add more. In fact, there's probably a Linux replacement for most of the Windows or Mac OS X software you're used to. At the bottom of the Applications menu you'll find an entry that says Add/Remove. Clicking on it brings up a browser window full of software that's available from the Ubuntu software repositories. Downloading and installing new applications over the Internet is as simple as checking a box and clicking Apply Changes. The new software will appear under the appropriate category of the Applications menu once it has automatically installed.
That easy installation method works only for the most popular software packages, but many more are available. When you become more experienced, you'll want to experiment with the Synaptic Package Manager--found on the Administration menu, under System on the top menu bar--which offers more-fine-grained control over software installation.
As long as you're connected to the Internet, the system will periodically alert you that new updates and security patches are available for your installed software. Applying updates is simple: Clicking on the alert icon launches the Update Manager, which allows you to review the available patches, but downloading and installing them is really a one-click process. Often it doesn't even require a reboot.