Correct,
Lua Code:
local Pets = someframe:CreateFontString(nil, somedrawlayer, somefont)
Replace
someframe with the frame you want to be the parent of the new FontString
The parent will effect the Fonstrings scale and when it's, shown/hidden etc.
Replace
somedrawlayer and
somefont with the relevent information depending on where in the layer stack you want the string displayed and the font/size you want the text to be displayed in. See the docs for
CreateFontString and see
this page for some of the in-game fonts configurations ie. GameFontNormal, GameFontHighlight etc. etc. etc.
You can't use
someframe (whichever that frame is) to create the FontString until after the frame itself has been created (The order that code is placed (runs) matters).