>I need to open the tables exclusively in a form that contains alot of update operations on different tables, the problem is how to open all of my tables sucessifully if other users in the system, so I need to give the user a message and try to open the failed table again until I open all of my tables.

you could attempt the open the table exclusively and trap any errors that occur., e.g.

Local lnError, lnCounter
Store 0 To lnError, lnCounter
On Error lnError=Error()
Use mytable Exclusive
Do While lnError<>0 And lnCounter<1000 && only try 1000 times before giving a message to user
  lnError=0
  lnCounter=lnCounter+1
  Use mytable Exclusive
EndDo
If lnError<>0 Or lnCounter>=1000
  Messagebox("Could not open table.")
EndIf
On Error