Here are a few quick tips to get you up and running.
To start an application, click on the "K" button on the panel (called the Application Starter) and choose an item from the menu.
Click the icon that looks like a folder with a picture of a house on the taskbar to access the files in your home directory using kfm, KDE's File Manager utility.
Choose Application Starter > Utilities > Terminal to get a Unix command prompt, or press Alt-F2 to get a mini command prompt window to execute a single command.
Choose the KDE Control Center item on Application Starter to configure KDE.
Press Alt-Tab to switch between apps and Ctrl-Tab to switch between desktops using the keyboard.
Use the right mouse button to access context menus for the panel, desktop, and many KDE applications.