Private Sub SearchReplace()
    Dim FindObject As Word.Find = Application.Selection.Find
    With FindObject
        .ClearFormatting()
        .Text = "find me"
        .Replacement.ClearFormatting()
        .Replacement.Text = "Found"
        .Execute(Replace:=Word.WdReplace.wdReplaceAll)
    End With
End Sub

private void SearchReplace()
{
    Word.Find findObject = Application.Selection.Find;
    findObject.ClearFormatting();
    findObject.Text = "find me";
    findObject.Replacement.ClearFormatting();
    findObject.Replacement.Text = "Found";

    object replaceAll = Word.WdReplace.wdReplaceAll;
    findObject.Execute(ref missing, ref missing, ref missing, ref missing, ref missing,
        ref missing, ref missing, ref missing, ref missing, ref missing,
        ref replaceAll, ref missing, ref missing, ref missing, ref missing);
}