You can book to repair it officially from the Microsoft website, (I'd provide a link but it won't let me post one, but it's quite straight forward, a quick web search) but I suspect it may be quite expensive. I usually look for a repair shop in shopping centres and places of sort. However, most do not usually have Lumia 930 screens as they are not so common so this is quite a challenge. If you can find a repair shop, it will set you back ~?30, that is, if they will repair it for you.