Matthew is right this is one longer term solution, but you still have to get the commands working first :)

Was there a reason you moved from using .. to using absolute pathnames when you moved the working command from the command line into Geany?  Unfortunately we can't see what was your working directory when you ran gcc in the command line, so can't trace the ../..s to see if your absolute directory paths are the same thing, but the most likely problem is that they are not the same.

 

See http://mrbook.org/tutorials/make/ for a somewhat abbreviated tutorial.

Specifically the minimal example that gives :

all:
	g++ main.cpp hello.cpp factorial.cpp -o hello

But with the command replaced by your working one of course :)

Note: that *must* be a Tab character before the command, no spaces.

Cheers

Lex