Hi!
There are multiple logs, most of them under /var/log/asterisk...
That said, if you look at the comments section of the page you posted you will see that Andrew says that to get CDR working you must setup ODBC and it's not covered by that tutorial...
I don't know if it covers all the step but Joel Snyder in the comments section tells you how to do it...
Good luck and have a nice day!
Nick