Team Planner is ready to use as soon as you install it. You can find the link in the Apps section in Jira’s top menu.
Upon clicking the link you will be presented with the Team Planner Dashboard which presents a list of all plans created on the instance. In case you do not have plans yet a message will be present instead of plans.
For your first steps, we recommend reading our guide on how to create a plan and add users to it: