Hello,
I am a bit new here and wonder if there is a test forum where I can create new topics, polls and in general can try out things before I participate in 'normal' forum discussions.
Just go to off-topic board:
https://bitcointalk.org/index.php?board=9.0and play around with creating threads, polls etc.
You can put a short disclaimer:
"I'm just testing forum options, please do not reply" and delete it once you're done. That's just so the mods won't ban you for spamming (but there's high level of tolerance in off-top)