[Waky]

For an conditionals you need a double equal sign "==", also the addon is "ShadowedUnitFrames" from what I've known

Try this code:

local actionFrame = CreateFrame("FRAME", "actionFrame", UIParent)
actionFrame:RegisterEvent("ADDON_LOADED")
actionFrame:SetScript("OnEvent", function(self,event,addonName)
   if (adddonName == "ShadowedUnitFrames") then
      local f = CreateFrame("FRAME", "myFrame", UIParent)
      .....some design stuff color and border.....
      f:SetPoint("CENTER", SUFUnitplayer, 0, 0)
      f:Show()
   end
end)