To compile the files just execute the command make as showed below: $ make
The command make will compile the .c files and it will generate the executable ones.
Once you have the executable files, in one terminal you execute the server with the command: $ ./server
Open a new tab on terminal and execute one of the clients executable files (client or clientOpenMp): $ ./client or $ ./clientOpenMp
After that, check the server output and you will see how long it took for the client application to run.
Feel free to play around and modify the code as you need.