While executing a manual test case, you have the option to create a new defect by clicking on New Defect. You can also click on the info bar, which suggests you to create a new defect, that appears after you mark a step as failed.
A new tab will open and you are able to document and save your defect. Please make sure you have pop-ups allowed. The information from the execution is automatically transferred and the test case as well as the execution are linked to the defect via a dependency. In addition, information from selection fields with shared value sets as well as text fields are also transferred, provided that these are named the same in the test case and defect. For more information on this topic please refer to the chapter Taking Over Field Values between Items.
After saving the defect, you can analyze in dependencies how to reproduce the defect and which test cases have to be executed in order to specify that the functionality is fixed.
