A single Test Design may require multiple separate test cases to fully cover the range of tests identified in the design. The structure provided by the "Demo1" project makes it easy to see the relationship between the Test Plan, each Test Design, and the Test Cases which have been created to support each design. Coverage reports can also be produced so that you can easily see which test cases are being used to test each system function.
Each Test Case identifies the component(s) to be tested, the test data that will be used, the expected outcome of the test and any special environmental needs or special instructions that are required. All inter case dependencies are also recorded, so that other tests that must be completed before this test can be successfully run are clearly identified. Test Lead provides special features and toolbars to help you to provide the required information quickly and easily, and in a consistent format.
(You may at this stage be thinking "This is a LOT of documentation. Do I really need to do it all?" The answer is simple - document what you think is needed, and no more. But remember, the real test comes when you are on holidays and someone else needs to run some tests in an emergency!)