I'm new to bitcoin and I'm only a junior member
Can you please help me to understand what is vtt.?
VTT? What exactly do you mean? What does the acronym stand for? I've never seen it being used on this forum, so i really doubt it has any meaning related to this forum.
What rank to join? / And how can I join?
You can't join a rank, you will gradually progress towards a new (higher) rank. Both merits & activity are required. See the stickies on top of this board.
https://bitcointalk.org/index.php?topic=1689727.0