As the Test Plan is used to aggregate Test Cases to be executed later, you can use two ways to create it. The first is to create an empty Test Plan and add Test Cases later and the second is to create a Test Plan with Test Cases based on the contents of folders from the Test Repository or Coverage panel on the requirement. Below you will find a list of possible options.
Below you will find instructions on how to create a Test Plan using the Create button, other descriptions of the methods you will find in the links attached above.
Steps
To create a Test Plan:
Result
You have created a Test Plan. Now you can add Test Cases.