New to Gnumeric -- attempting to plot data

[Richard Owlett <rowlett cloud85 net>]

Although I used spreadsheets back in days of CPM/80 and WinXP,
I've not used any in *DECADES*.
My OS is Debian Stretch (9.8).
The version of gnumeric is 1.12.32 .

I wish to plot the data in C30:C65 against the data in A30:A65.
I wish the labels on the x-axis to run from the value in A30 to
the value in A65.

I do not find the manual at
  https://help.gnome.org/users/gnumeric/stable/gnumeric.html
very helpful.

Help please.
TIA