The ONLY way to get ring/text/timer tones into a non-jailbroken iPhone is either via the official Apple 'tone store' or with a computer and iTunes, Apple allows no other methods. You first have to trim the audio down to 30 seconds (longer clips will be rejected), then you have to save/export it as M4A/AAC, then you have to change the file extension from ".aac" or ".m4a" to ".m4r".
Once you've done that, you have to connect the phone to iTunes and drag the m4r files over (I think into the left sidebar? It's been a while). If the clips are too long or weren't saved in the right format then iTunes will just flat out refuse to copy them.
Unless things have changed recently, Apple does not allow you to download and install ringtones from random websites or emails using the phone itself. If you don't have a computer and iTunes then your only other option is buying stuff from the store (or jailbreaking).