Crescendo

I’m having a bit of trouble with crescendos.
I know how to use them, but I don’t know how to apply one to a single note—for example, a whole note.
It’s easy to do between two notes—like starting the first note pianissimo, adding a crescendo, and then having the second note be fortissimo.

But I don’t know how to create a crescendo on a single long note.
I can’t seem to set it up so a single note starts pianissimo, goes into a crescendo (or decrescendo), and then reaches fortissimo.
Could someone help me?

Where is the difficulty?

One way, use the Shift-D Popover, enter p<f.

Select the note with your mouse cursor then (1) do what @Andro suggested or (2) expand the tools on the right of the screen, click on the f then click on the hairpin crescendo symbol.

Thank you very much for the help.

My pleasure.