You need to select the screw and arrow settings icon on the page Content > Product Reviews and Add Fields.
To do this go to Content > Product Reviews in your administration panel, click the hammer and screw icon for settings next to the review to the left of the screen and click "Add Field" and select the field(s) you want and save.
In the case that you want text to be entered, you need to select a single or multi line answer, however there are several other options available.
