Hiya, so questions like this can be found in the Help section of our forums in the FAQ. Feel free to take a browse and look for anything else you're not sure about there.
https://smgclan.net/misc.php?action=help&hid=18
To answer your question though, a reply to a forum post is counted as a post (but not a thread), and a thread (a topic you start) also accounts for a post as well as a thread.
Locked.
*flails*