New members posts go through a short moderation period (5 posts or so) and have to be read and approved by a moderator/administrator. Sometimes there is a short time from you posting the post and it being read and approved and showing up on the forums. Other times, it may take longer depending on who is online to moderate, what forums those individuals moderate compared to what forums you have posted in, or how busy the admin team may be at any given time during the day. Hope this helps your understanding!

Be well