To tag a response simply select it and then click on the tag that you want to assign. You can select multiple responses to give these responses the same tag.
You can use the arrow keys to move from one response to the next.
To tag responses in another language, click on the language drop-down in the top-right corner and select one of the other available languages. This option is only available when you have a multilingual survey.
When you have activated sentiment analysis, a drop-down menu with the three sentiments, negative / neutral / positive, will be provided once you select a tag. Click on the appropriate sentiment to apply it to the selected response(s).
Use the filter options on top to quickly find tags containing the same word. Type it in the search box above. Additionally you can decide whether the answer must contain the full keyword or only part of it.
Or use the Frequently used words to first have a look at which words were used most often in this particular question. It can help in deciding what tags to create, and which responses to first have a look at.