Eclipse allows you to maintain configuration options and preferences from debug session to session via the "debug configuration" mechanism. The first step in debugging under Eclipse is to create such a configuration.
First, select "Debug" from the "Run menu." Second, in the left hand pane of the Debug dialog, double click on "C/C++ Local Application."
You should see something like the following:
From the tabbed dialog on the right, you can select various different configuration options. For instance you can select the executable you wish to debug, the arguments you wish to pass to it when it's launched, the environment under which it will run, the debugger to use, etc.
You may have to experiment with the options to find the combination that works best with your operating system and other installed software.
On a typical WindowsXP installation, for example, the following settings in the Debugger tab work well:
If the debugger cannot find the source for your program to display, try unchecking "Use default" in the Arguments tab.
If you want to debug library unit elaboration, leave the entry point as "main" and let the debugger stop there. You can then step through the elaboration of all the library units.