You will always find the actionbar on top of a window. It very often regularly changes it's content dynamically without affecting performance or impeding other user actions like closing current the window or creating a new item by clicking a button in top right corner.
The list will be filled as new tags are added. Simply click on a Tag that you wish to use. If you want to edit the name or delete it, just click the button on the right of the selected Tag name.
Actionmenu will always show in a place of actionbar. It changes actionbar content and presents you the actions that you can perform on selected Tag. Here you can choose between deleting a tag or editing it.
When you Close the Tags window, you will see these Tags you have selected are now shown in Data tab. If you wish to see more tags in this window, you can simply scroll horizontally on a view where Tags are presented