Python Threading

I have a basic python script that runs through a list of subdomains from a file using a while loop to get the http error codes. I have made this but unfortunately i don't know how to thread this to make it run faster (I want to run 15 threads). The script is 40 lines, but the thing that need threading is only 30 lines. I assume you use [login to view URL] to be able to allocate the threads, however i don't know how this works with a while loop. I am on a tight budget as I am still a student. Many thanks, Jake