That's okay! 

When filling out your application, put all of it in English except your title, how you want your name listed (unless it's just your username), and the quotes/phrases.

(I would prefer if you listed the bolded items above in both English and your language so I know what it means in order to make you a better cover.  But it's not mandatory.)

Any text for my reference (ex: story description, story mood) that won't be on your cover needs to be in English.