You can launch (open) a program in any of several ways.
Double-click an application’s icon in the Finder.
Click a program’s icon on the Dock, Sidebar, or the Finder toolbar.
If you’ve added the Applications folder to your Dock (or, better yet, a folder containing aliases of only the programs you use), hold the mouse button down on it until the list of its contents springs open. Then click the program you want (or even type the first few letters of its name and then press Return).
Highlight an application icon and then press -O (short for File→Open) or -down arrow.
Use the submenus of the menu’s Recent Items→Applications command. (You control how many programs this feature tracks using the System Preferences pane described in Tweaking the Scroll Bars.)
Mac OS X stores a list of your recently used programs in a text file called com.apple.recentitems.plist, located in your Home folder→Library→Preferences folder. And with about $1.00, that information will buy you a cup of coffee in most restaurants.
Open a document icon in any of these ways, or drag a document onto the icon of a program that can open it (whether in the Dock, the Finder toolbar, the Sidebar, or in ...