Usually you want to have historical data about Iterations /Builds quality. For example, if build 1.0.0 has 50 failed test cases and build 1.0.5 has 15 failed test cases it is clear that quality improves over time. Test Plan Run supports this concept so you may run the same test plan over different builds and have run results stored in the TargetProcess.

Test Plan Run may be created for specific Iteration or for specific Build.

The following steps should be performed to create complete test plan run:

1. Add build (General -> Builds -> Add)
2. Add test cases and test plan
3. Add test plan run, bind it to build and assign to QA Engineer

Also you may run tests from this page ( Run action) and view run results.