To set a breakpoint, for example at the call to
in one of your functions:
Meta+Ctrl+Qin Emacs emulation).
Toggle Breakpoint. The symbol
+is highlighted red indicating that a breakpoint is set.
When the breakpoint is reached, a Stepper tool is invoked, allowing you to step through the code, add further breakpoints, and so on. See The Stepper for more information about the Stepper tool.