Hello !
Your requirement is as follows :
1. When ever a sales order is created, workflow should trigger.
2. The triggered workflow should send an e-mail to approver stating that sales order is
awaiting for approval.
3. If the approver rejects the sales order, same to be intimated by e-mail to initiator.
If above is your requirement, there is no standard workflow for the same.
You've to develop a custom workflow.
Regards,
S.Suresh.