1. start IDLE

“Python 2.5”→“IDLE（Python GUI）”

2. open your source file window

From python shell, select file->open...

3. show debug control

From python shell, select Debug->Debuger

4. start running

From the source file window, select Run->Run Module

5. debugging with Debug Control

Step: step into

Over: step over

Out: step out

Go: run...

breakpoint: set and clear breakpoint in the source file window with right click menu at the line you want