unicode??

hi
I have string I want do unicode
to this string using "system.text.encoding.unicode"

but how can I write this code

Sorry, where is this string? Are you saying you want to write a string somewhere as unicode or read it? Are we talking about text in a file?

no I have string in arabic language
I want use unicode to write this string
but I dont know the way

Write this string where? To a file? If you want to write it to a file then please specify that you want to write it to a file. If you want to write it elsewhere then please specify exactly where.

I want write it in text box
thanx

Then, as always, you simply assign your String to the Text property of the TextBox. You have to ensure that the Font property is set to a font that supports the characters you want to display.

A clear and complete description of what you want in the first post would be good in future. I understand that English is not everyone's first language but that means you need to try harder to post clearly, not less. Not saying that you wantred to display this text in a TextBox when that is pretty much the critical bit of information is just a waste of our time and yours.