If you don't require 64 bit support, consider downloading "codeblocks-12.11mingw-setup.exe"
It packs its own 32 bit mingw and has everything preconfigured for you.
Otherwise, if you still need to compile amd64 apps:-
Assuming you extracted to D:\Mingw64, under the "Tool Chain Executables" tab, set the "Compiler's Installation Directory" to "D:\Mingw64\bin", Then click auto-detect to check whether code::blocks likes what it finds.
If everythings Ok, make sure the rest of the fields are as follows:-
C compiler: x86_64-w64-mingw32-gcc.exe
C++ compiler: x86_64-w64-mingw32-g++.exe
Linker for dynamic libs: x86_64-w64-mingw32-g++.exe
Linker for static libs: x86_64-w64-mingw32-ar.exe
Debugger: GDB/CDB Debugger...
Ressource compiler: x86_64-w64-mingw32-windres.exe
Make program: mingw32-make.exe
Click on the "Additional Paths" tab and enter the following line:- (the path is correct for ver 4.7.4,the one you downloaded. It ends with 4.7.3)
D:\Mingw64\libexec\gcc\x86_64-w64-mingw32\4.7.3\
Click on the "Search directories" tab to the imediate left "Toolchain Executables"
Add the following paths:-
D:\Mingw64\include
D:\Mingw64\x86_64-w64-mingw32\include
D:\Mingw64\x86_64-w64-mingw32\include\c++\4.7.3
D:\Mingw64\x86_64-w64-mingw32\include\c++\4.7.3\backward
D:\Mingw64\x86_64-w64-mingw32\include\c++\4.7.3\x86_64-w64-mingw32
D:\Mingw64\lib\gcc\x86_64-w64-mingw32\4.7.3\include
Click on the "linker" tab and add the following paths:-
D:\Mingw64\Lib
D:\Mingw64\x86_64-w64-mingw32\lib
And finally click on the "Compiler Settings tab", Click on "Other options" and add:-
-m64
One last thing-> remember to save those settings to disk!
If it crashes while you test this new config, you might wish you had!
Do this (I think) either by "File->Save Everything" or restarting code::blocks ...without another instance running.