You need to be at least jr. member to post images. But you can buy Copper Membership --> https://bitcointalk.org/index.php?topic=2385104.0

That will allow you to post images if you don't rank up as a jr member because you need to have at least 1 merit and 42 activity to become one.

Learn from the Announcement sections and just look how they've designed it. I'm not quite sure if there's a tutorial for making one but I think there is and someone will post it after me.