Add error responce

I have written the function:

Code:

---

  Public Function getInternetFile(ByVal fileURL As String) As String

        Dim webconnect As New Net.WebClient()
        Dim readFileURL As New IO.StreamReader(webconnect.OpenRead(fileURL))
        Dim fileInternetContents As String = readFileURL.ReadToEnd
        readFileURL.Close()
        webconnect.Dispose()
        Return fileInternetContents

    End Function

---

Which opens and reads in a file on the internet.

How do i add an error message. ie if the function is called but the fileURL value dosent exsist, then I want it to return an error message. At the moment it will just crash if fileURL is invalid!

THanks!

Use try catch blocks