How to add defects I find ?

You can create the defect at the time execution and associate the same to Test Case/Test Step units. Also, you can associate the existing defects to Test Case/Test Step units.

1: Execute a Test Cycle.

2: You can search for existing Bug/Defect searching with a summary or JIRA issue ID.

3: Also, you can create a new bug or sub-task issue by clicking on the 'Create Bug' button. 

Refer to this help guide for more information.