Why wont my iphone 4 let me update to ios 7?

My iphone 4 wont update to ios 7. Any ideas?

IOS 7 is only made for iphone 5, 5s, ipod 5, not for less then 5.

IOS 7 is currently in beta testing for Apple Developers only. It is not yet available to consumers. It will be released to consumers this fall. That is why you won't be able to download it yet.

Compatibility:
iPhone 4* and above, iPad 2* and above, iPod touch fifth generation.

*Not all features will be available on all devices.

You must need UDID activation for instilling Beta i OS 7 & beta version May have some bugs so its recommended install i OS after coming final version there are some tricks for installing i OS 7 without UDID activation:

First you need to register your device's UDID with a site like http://www.instantudid.com/ before you can activate iOS 7.

Hi wats up ok my phone dropped in water what can I do my light on the phone won't go off and I can't touch the bottom of the screen and I am trying to upgrade my phone but it won't let me do that so I need help please