How to update my iPhone 4 without an computer?

I tried deleted all my apps like the phone said and it still won't update and then I found I have to use a computer but I don't have a computer how can I do this without an computer

Generally you can just going into settings>General settings>software update you might have to connected to a Wi-Fi network of you freed up space on your phone. What ios version are your runningn?

If you are jailbroken then you will need to use a computer to restore and update your iOS version. IOS update over the air (OTA) is supported since iOS 5.1.1