Trouble with custom makefiles

[pegasus2000]

How does Code::Blocks manage the custom makefiles ?

I have written a probe makefile with this only row

echo $SOURCES

I expected that the system returns the list of sources files that are
present in the project, so that the makefile can compile them.

Instead the environment variable is empty.

So, how can I write a custom makefile ?

[stahta01]

Do you know what an makefile target is? (The word before the :     )
Code::Blocks calls the make command with an target.

C::B normally uses the target release and debug.

Makefiles tend to use "all" as the top target.

Tim S