Documentation are available here:
Config of repository of Test
go to Testing board
Instead of using Test Set, use the Test Repository to organise your tests cases
and then for a functionality, all the test cases
once you are in Xray via the Testing Board
use the menu button to navigate to see all test cases or all test executions or all test plans
Create the Test Execution
Initial configuration :
Under Test coverage select the item type that should be tested.
Under Defect Mapping select the item type that will be used when you create a defect from the testing board
Under Test Environment select the environment where you will perform your test or create a new environment (Only if it doesn't exist).
Save your configuration