How to set predefined macros in Code::Blocks

Is there a way to set some predefined Macros for my local installation of Code::Blocks.

To elaborate on that, basically I would like to have certain blocks compiled only at pc and not anyplace I send the code to. One way to achieve this is as follows:

#define MYPC
#ifdef MYPC
 //do something
#else
 // do something else
#endif

I was to achieve the same thing, but I don't want to include the line #define MYPC and woud like to add this somewhere in the IDE. I know how to do this in Visual Studio, and I think it also exists in Code::Blocks as well. Спасибо.