Hello KONSTANTINOS and welcome to the ArtRage forums
By default the app should open in the same language as used by the Operating System. ¿Eres español?
If you want it in another language without changing the OS language then for the Desktop versions do the following:
Launch ArtRage, in the Menubar go to: Help > Select Language > English.
In the window that opens click OK and then restart ArtRage.
It should now be in your preferred language.