[Koha] Publisher question - Changing Background color

[jeff haskell]

My talented listmates,

 I have a deadline for tomorrow and just was presented this challenge
by a library patron.

 They want to change the "background" color inside of a .png graphic
to pink in Publisher 365.

 It's a free clip art with the word Sheriff inside a circle and they
want to keep the black lettering for the word Sheriff as well as the
lines coming to points inside that graphic.

 They just want to change the color "behind" and round the word Sheriff to pink.

 This is for a menu for a small restaurant they just started.

  Would you be so kind as to share the steps in Publisher?

 I tried Page Design  Background  More Backgrounds and choose pink in
the color palettes selection but ti changes the work Sherrif form
black lettering to pink - not what this patron wanted.

Thank you so much.