The tags are added fully automatic and there is no option to add tags manually for now. That being said, we really want to make the tagging algorithm better, so hit me at human@finch.io with your case.
I basically used reddit's Bigquery data for the dataset (it's huge!). My algorithm and code is here[2].
[1] https://www.youtube.com/watch?v=gudnFNBXc58
[2] https://www.reddit.com/r/learnmachinelearning/comments/6hqd6...