After selecting the Team project, next comes the selection of the existing Test Plan from the Team project or creating a new one. The following screenshot has two test plans already from which we will select the first one to create all Test Plans. The window also has an option to copy the URL to open the Test Plan in the Testing Center. For example, the URL for the first Test Plan in the list would look like mtm://my-pc:8080/tfs/defaultcollection/p:TestTeamProject/Testing/testplan/connect?id=2, which would directly open the Test plan when you browse to it.
After selecting or creating the Test Plan, you can see the Testing Center