headers.h contains clk functions, it should be included anywhere the clock functions are used.

To get time call:

getClk();

You can use Makefile to build and run your project

To compile your project, use the command:

make

To run your project, use the command:

make run

If you added a file to your project add it to the build section in the Makefile

Always start the line with a tab in Makefile, it is its syntax