FFmpeg's internal libraries (libavcode, libavformat and a few more) have a pretty complex code structure. You will need time to understand how basic things work, then you should try to write some simple test applications, and only then you will be able to replicate given command.
There are quite a few tutorials available how to use FFmeg's libraries (some of them use obsolete API), please also check a demo code in “doc/examples” directory.
Hope it helps !
From Comments:
Check examples/muxing.c sources from the latest FFmpeg version. Try to provide an URL instead of output file. Check documentation/sources for avformat_alloc_output_context2()
function. Then you should get the basic idea how to add streaming support