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No need for the #. Just keep every word lowercase and yes they go in the tag field. I'm not sure if or how they work if you put them in the main text of your post.
Two words like introduceyourself go together as one.
I believe they have recently limited the amount of tags you can use so make sure to use whatever is most relevant to your post so that the right people (who would want to read it) will read it.

Thank you but i dont real understand it.