need help with FileStream for writing text

[dunfiddlin]

No it isn't. You wouldn't normally use FileStream for text but it's actually not that difficult.

Dim writer As New IO.FileStream(filename, IO.FileMode.OpenOrCreate, IO.FileAccess.Write)
        Dim s As String = "Name Surname" ' for example
        Dim b(s.Length - 1) As Byte
        For i = 0 To b.Length - 1
            b(i) = BitConverter.GetBytes(s(i))(0) ' it will always be one byte for a character
        Next
        writer.Write(b, offset, b.Length) ' bytearray, position, length
        writer.Close()