What tags should I use to make a user manipulated UI?

Thanks for posting.
This is a pretty broad question that could potentially involve several moving parts.

I would probably create a grid template (a series of panels) where textfields and labels can be added and removed and use that as a basis for placing new things in on action.

Then select a class (which would be a pre-made textfield/label group) place it using the concept of <create> and <delete>.

Then you would need to set [preferences:] for what and in which grid panel they are placed and use that to recreate them later as a series.

I would review the above concepts in our documentations site and see if you have any questions.

Do I need to learn JavaScript to do something like this?

You should be able to manage this without JS, just a firm handle on classes and preferences.

Thank you.