Make sure to chmod it into an executable. You can also place it into your bin folder where your scripts are located. Edit the file to your pleasing since it is for Mac os intended because I use osascript for the notification banner, afplay to use a built-in sound and the say command to convert text to speach which I think is mac specific too. And the only three flags you have to use to set a custom time is:
--work 25 --break 5 --sessions 4
The args for work and break are to set in minutes and the arg for session speaks for itself i think.