Debugging Program with ABAP Debugger

Activate the Debugger before executing your ABAP program

System -> Utilities -> Debug ABAP/4

The purpose of the debugger is to allow you to execute your program line by line. It also allow you display the data as you execute the program. (double click on the varaible field name and it will be display)

or after program have been executed,

Run transaction SM66 and find your work process.
Select the line of your work process and double click on it
Click the debugging option.
If this is a custom program, you can put a wait statement in the code to buy yourself some time.