Trying to Build after adding some new files

Hello there! first time here for me! please, be patient!
We (My mate and I) are trying to make simple chages to the source code, adding new ".c" classes ¿What have we got to do to be able to Build the new code? It is very complicated because of there are a lot of autogenerated "cmake-files". For example, we are trying to modify the "update_file_list.sh" scritp for making it recongnise ".c" extension files, but it is not working!! return errors at "cmake/SourceGroupFunctions.cmake:23" (or :24).
Thanks in advance for your help!
We (My mate and I) are trying to make simple chages to the source code, adding new ".c" classes ¿What have we got to do to be able to Build the new code? It is very complicated because of there are a lot of autogenerated "cmake-files". For example, we are trying to modify the "update_file_list.sh" scritp for making it recongnise ".c" extension files, but it is not working!! return errors at "cmake/SourceGroupFunctions.cmake:23" (or :24).
Thanks in advance for your help!