When I give the code line DoCmd.GotoTorecord , ,acFirst, I get the error message :
Run-time error 2499: You cant use the GotoRecord action or method on an object in Design view.
I am pasting the whole vba code block here

DoCmd.GoToRecord , , acFirst
DoCmd.GoToRecord , , acNewRec


[Forms]![DietMain]![DietSubform].[Form]![Item] = rst![Item]
[Forms]![DietMain]![DietSubform].[Form]![SN] = rst![SN]
rst.MoveNext
DoCmd.GoToRecord , , acNext
Loop Until rst.EOF
rst.MoveNext
rst.Close 'close recordset.

End Sub