I want to add Idn A Converter ( I found it here http://www.phpclasses.org/browse/package/1509.html#download ) To registration page. My English is not good enough so I explained it with a photo.
Please take a look at a sec.

more explanation:
I want to allow speacial character like æ ,€ etc. so that people can sign up domains including these chars. when you sign up with the name of "æ.com" it should encode it to "xn--6ca.com" but there is some specialities when a letter comes right or left side of an IDN. For example if you try to sign up "æro.com" it will encode it to "xn--ro-0ia.com" not to "xn--6caro.com" æ ro ro is in middle not at the end.