To compile a C program, VS2015 provides you a command line intepreter called cl. To use it, you need to setup the development environment. Luckily, VS2015 also provides a batch script to do this for you. The script is called VsDevCmd.bat and is located inside <VS2015 installation folder>\Common7\Tools.
The most basic usage of cl is:
cl your_first_program.c
If you wish to add extra libraries, you need to append the %INCLUDE% and %LIB% variables. To do this just use the SET command. For example, if you want to include Python.h, you do the following:
SET LIB=%LIB%%PYTHON_HOME%\libs; SET INCLUDE=%INCLUDE%%PYTHON_HOME%\include;