Employees can raise requisitions for items required either by them or the department they belong to. Requisitions can be of 2 types

1. Internal Requisitions
2. Purchase Requisitions

Internal requisitions are catered internally within the organization once the requisition is approved. Normally this means that the items exist within the organization and do not have to be procured from outside or sales orders are generated within the organization. Purchase requisitions have to be met by procuring the items from external suppliers. Hence, once the requisitions are approved these requisitions have to be converted to purchase orders.
I have illustrated the steps to be followed to convert the requisitions to purchase orders below.

Login to Oracle apps
Responsibility: Purchasing
Navigation: Management > Manage Buyer Workload
Click on Find button. As the search criteria we had taken the default value as,
Assigned = No
Approval Status = Approved
Thus only the unassigned and approved requisitions will be displayed on the next form.
Select a buyer for which you want to create the purchase order by entering the buyer name in the New Buyer field.
Select the requisition(s) that should be assigned to the buyer.
Save the form.

Now navigate to AutoCreate on the same menu.
Ensure that the Buyer shown on this form has selected approved requisitions previously. Click on Find button.
Select the requisition(s) for which the PO should be created.
Ensure that the fields, Action, Document Type and Grouping reflect the correct values. Click on Automatic to create the purchase order automatically or Manual to create the purchase order manually.

Automatic PO creation

After clicking on Automatic button in the previous form,
We shall ensure that the details for purchase order creation are correct. Enter a supplier.
Click on Create button.
The purchase order has been created for both approved requisitions into a single purchase order.

Manual PO creation

We shall now create purchase order by clicking Manual button on the AutoCreate form.
Select any requisition(s) for which purchase orders have to be created.
Select a supplier
Click on Create
Click on Add To Document button
Click Create button
Now the purchase order opens with the new purchase order that is created for the selected requisition.