Alter an Image

I need to alter this Mac system upgrade popup image (attached) to say something new. Heading: "Recommended Upgrade: Global Air Transport System" Explanatory Text: "The current system you are using is becoming obsolete and no longer suitable for reality. This may cause your Earth, society and economy to run increasingly erratically and risk eventual failure. Would you like to begin transitioning towards an upgrade to resolve this issue?" Buttons: “Yes” “No” Logo: Sustainable Sky logo attached This is an easy job that shouldn't take much time at all. The resulting image needs to be given to me is .psp, vector and .jpg format Thanks