Help->Current describes the task currently active.
Pressing 
Atom->Create and then 
Help->Current on the top 
menu, a window 
Help Atom Create pops up showing how to use the 
Atom Create dialog. Pressing then 
Cell->Modify and 
Help->Current, a window 
Help Cell Modify replaces the 
previous help window, showing how to handle the 
Cell Modify dialog. 
Help->Current is conveniently set up as the first option 
in the Help menu.