First Generation IPhone Trouble?

I know what you are thinking. You still have the first generation IPhone? No I don't. I cancelled the phone plan for that one a long time ago. Now I have an android. Anyway, this Friday Warped Tour is coming up where I live. I found the old IPhone recently. I know it doesn't have a calling or texting function now but i wanted to use the apps. I want to have twitter notifications and the Warped Tour 2013 app. But whenever i try to download an app, it says that it requires IOS 5 or higher. I can't use my Android for the notifications and Warped 2013 App because it is not available. I got the old IPhone when it first came out. How do I update my old first generation IPhone? I

The original iPhone may soon be a collector's item but it only runs the earliest iOS apps.
I know of nearly 25, 000 of them available that will work. This has by far the best list,
https://itunes.apple.com/...?mt=8&uo=4