Request Task Planner - Additional properties

We are using HPSM 9.41 and I succeedded with activating the "Additonal Properties" on a Request Model with 2 Request Tasks.

I also succeeded with creating an Input and Output field - I want either the Closing Comments or the Output from Task1 to be used in Task2 as Input - but I cannot figure how to do that - do you have any suggestions?

I am struggling with finding any 'official' documents, which describes how to do it - I have found "Application Setup help topics for printing" p. 91...

Thank you in advance.

Kind regards,

P.S. I hope my question also reflects what level of experience I am on -.-