How can I assign a card to a person?
To assign a card to a person, click that card and look at Card Details on the right. Scroll down a bit and click on the Assign to button located under the card description. Choose a person from the drop-down list.
Note: In this list, you will see only those people with whom you have shared your board.
To remove an assigned person from the card, simply click on their name in the same drop-down list.