You can use the Menu to launch programs and to initiate many administrative functions. Simply click on the KDE Menu launcher to pop up the KDE Menu. To launch OpenOffice Write, for example, click KDE Menu => Office => Word Processor. Other programs can be launched in the same way.
Notice that your most frequently used applications will appear at the top of the Menu. These will change over time as you use more applications and as you use some applications more than others. The applications that appear in this section of the Menu are sorted from top to bottom in order of frequency of use. You can configure this section so that it contains the last five (or any other number you choose) applications you have used rather than the ones you use most frequently.
Some of the other options available from the KDE Menu are access to your Home folder, and Help (the little life ring). The Actions section provides access to settings and to the print system configuration. There is also an item that shows the most recent documents on which you have been working and allows you to select those for immediate launch without searching through your folders for them.
There are also options to lock your current session, logout, and even to switch users.