Android Question how to share file for android app to write /edit?

Private Sub btnViewImage_Click
    Dim FileName As String = "b4a.png"
    File.Copy(File.DirAssets, FileName, Provider.SharedFolder, FileName)
    Dim in As Intent
    in.Initialize(in.ACTION_VIEW, "")
    Provider.SetFileUriAsIntentData(in, FileName)
    'Type must be set after calling SetFileUriAsIntentData
    in.SetType("image/*")
    StartActivity(in)
End Sub

Private Sub btnShareFile_Click
    Dim FileToSend As String = "Message.txt"
    File.WriteString(Provider.SharedFolder, FileToSend, "jaklsdjalksdjalskdjasld")
    Dim in As Intent
    in.Initialize(in.ACTION_SEND, "")
    in.SetType("text/plain")
    in.PutExtra("android.intent.extra.STREAM", Provider.GetFileUri(FileToSend))
    in.Flags = 1 'FLAG_GRANT_READ_URI_PERMISSION
    StartActivity(in)
End Sub