You may go to Sales-> Orders and click on the 'Add' icon on the top right corner to insert orders. You will have to fill in the customer's basic information, shipping information, payment information and add the products according to SKU.
Please note:
1. When the order is added successfully, it will not add new customers to your store. The system assumes that the order is made by guest checkout. If you need to add new customers, please go to "Sales"-> "Customers" to add a new customer and link the customer to his order.
2. Shipping cost and tax are not included in total value of the order. When the order is generated, you may edit the order to complete information such as tax and shipping cost.