Grammar is important. I think what you mean is
how i can display [bytes that i got by converting a string] in a visual studio C# textbox?
I'm not sure what you mean by "bytes that I got by converting a string". But I'll assume you mean an array of bytes.
First of all, to set the text of a textbox you would use:
textBox1.Text = "Hello";
To convert a byte array to a string of hex digits you might use something like this:
byte[] myBytes = new byte[] { 72, 101, 108, 108, 111 };
textBox1.Text = string.Join( " ", myBytes.Select( x => x.ToString( "X2" ) ) );
This results in "48 65 6C 6C 6F"
Or if you want to recover the string from an array of bytes you can use:
textBox1.Text = Encoding.UTF8.GetString( myBytes );
...or whatever encoding you are using.
Not sure which of these (if any) you are actually after.