The profile you are referring to has a "Sources" section.
As John Vickery said click the edit field ,
then scroll down to where you see the Sources section
add sources there
then click save
Jerry Newell .. I found a couple sources for Ella Leona (Barnes) Newell and added them to her profile to provide you with two examples of how to add basic sources.... * source or <ref>[(source)]</ref> ...
I also deleted the un-sourced status as her profile is now sourced.
The best to your work ..
C'est Bon .. JSGB
P.S. JOhn's right read .........