To step through the program a line at a time, type
<userinput>thread step-over
</userinput>. When the program gets to a function call, step into it by typing
<userinput>thread step-in
</userinput>. Once in a function call, return from it by typing
<userinput>thread step-out
</userinput> or use
<userinput>up
</userinput> and
<userinput>down
</userinput> to take a quick look at the caller.