Breakpoints

I think this is a basic question but how do I go about putting on
breakpoints and then how do I "use" the breakpoints to determine things
like what variables are being called on? This stems from a previous email
where someone suggested doing the following to locate rotating text:

*...Or maybe run around to the other side where the text actually gets
drawn to screen in vcl/unx/generic/gdi/salgdi3.cxx and put breakpoints on
the two cairo_matrix_rotate calls and examine the backtrace then to see
where it all comes from.*
*
*
Thanks in advance, learning as I go.


Joel