[glade--]glade newby please help

hI list

i just want to do a simple user interface using glade
i have built the interface (two simple buttons)
now i  want that every button run a c application
 for example i have done a c program called sing.c
i want that a user can run the program clicking on a button

i dont' know what i can do to do this, i dont' know how to change
in the callbacks.c.also i dont' know if is possible to
write a c function using for example 
i
nt main (){...
.........

because in the project there's  a main.c file ,so i can creat a conflict 

please explain me whit an example (
or better send me a simple example file
where  a button run an external c executable program

thanks

sorry for the newby question

regards


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Mauro Venanzi linux ru250233
hall2001 athlon-xp rm 135009 on Suse 8.1