3) How do you create a test case, link to a user story, add to sprint, and assigned to a tester?

We will first go to jira then we will go to our project in that go to backlog , then go to create issue select the issue type as test press enter.
ex: check the correct credential drag it to the running sprint or planned sprint. on the right side you will
see the link option & link it with whatever user story you want to create. and then press create.