How do you get app store?

your iphone should have already come with your app store downloaded, if it isn't then you either need to make sure you have an iTunes account or ask your local store where you bought that phone from why your phone doesnt have the app store. (if your iphone is like normal phones it should already have it) incase they say you must download it or something, make sure to ask THEM how because some iphones can be different than others depending on if it's 3G, 3Gs , or OS