make a cookie to a server programmed in c

I have a program in c, the program is a server, now I want to make a cookie in the server that register only the time and have an expiration, and only can have a by user. where can I begin? I leave my server code, and the source of the original code

https://1drv.ms/u/s!Ar-Rn3yNmAvtgRuv8GoKe48DrCuU

original

http://ift.tt/2cydmOV