In order to add work log to your issue you need to select one of the cells in the row that contains the issue (1) and click button Add (2). A dialog will appear (3) that allows you to type in information regarding the work log. The dialog resembles dialog found in Jira, so it stays intuitive and ease to use.
In order to check worklogs reported on an issue, select one of the cells in the row that contains the issue (1) and click button View (2). Dialog will appear showing list of all worklogs on the issue (3).