TestRail test cases are grouped into test suites. A test suite is created for specific functionalities.
These test suites are called as Section in TestRail. For each specific functionalities or modules, you can create different sections.
A section can be created by clicking on Add Section option on the right side of Test Suites & Cases section.
For example, if you want to write the test cases for Login functionalities, then create a section named Login and consolidate all the test cases for Login inside this section.
You can further divide each section into separate subsections to drill down further.
To write the Test Cases for a specific section click on Add Test Case option and write the Title of the Test Case and press Enter.
A Test Case consists of Test Summary, Pre-Condition, Test Steps, Expected Result. To complete the test case, click on the Title of the Test Case and click on Edit button.
It will open the Test Case design window with all the customised columns. The user can design the test case and click on Save to save the test case.
Note: One can customise the columns as per his or her requirement that will be present in the Test Case design screen. This can be done through Administration->Customization.