How to set Deltas in TrueType Instructor

Hi everyone )
I’m a newcomer in what concerns to hinting.
When I’m doing TrueType hinting in a good old FontLab 5 I choose the Final Delta tool and push it to right corner of the pixel grid.
In Glyphs app I see there is a way to create Delta parameters for each font-size.
Could you please explain me how can I create Delta parameters. When I chose delta (shortcut E) it shows me this:

Thanks a lot!

You set a pixelsize, you add a delta via the context menu or the shortcut, you make sure it selected, and you press the up/down arrows.

See the handbook in the chapter for all details.