You have two IF statements, and only one END IF.
You actually do not need the second IF at all. A value can only be Null or Not Null (there is no third option). So if does not meet the first check, you don't need to check the second thing, i.e.
Code:
Private Sub Form_Open(Cancel As Integer)
If [CWS] Is Null Then
MsgBox "New Users Must Register before proceeding! CWS, First and Last Name are Required to proceed.", vbOKOnly
DoCmd.OpenForm "AdminRegisterUsersForm"
DoCmd.Close acForm, "AdminVerifyUsersForm"
Else
DoCmd.OpenForm "Main_Menu"
End If
End Sub
Also, it is "DoCmd", not "Docmnd" (no "n") and "CloseForm" is not a valid command.