Click on a play button to listen to a verb.
Decide if the ending -ed is pronounced t, d or id and type (or select and "drag and drop") the verb in the white box in the correct column.
Click on the check button.
If it's the right word, the white box will disappear and the word will be written in its place.
If it's not the right word, the word will remain in the white box. You should try another column.
The first row has been done for you as an example.

(This is not a vocabulary exercise. It's not important if you don't know the meaning of some words.)