First you have to include Output.h:
Then you can use the orxout() function instead of std::cout (note: printf is obsolete). orxout() works almost like std::cout, but you can assign a level to your output:
orxout(user_info) << "This is some cool output!" << endl;
Every output through orxout() will be sent to the console, the logfile and the in-game-shell. There is a configurable maximal output level for every device. If the level of your output is > the maximal level of a device, it wont be displayed. But don't use orxout(debug_output) all the time because the user SHOULD be able to deactivate your output unless it's REALLY important.
See Output for more information about levels, contexts, and the general usage of orxout().