Automation of posting of invoices

Automation of posting of invoices

Hello Community, 

This is my first project on Zoho to establish financial statements for a company, I recorded the sales directly in manual journal and I recorded the expenses in Purchases==>Expenses. Then I checked the report if it is auto posted and reflected on Income statement & Balance sheet, but only sales got reflected and not the expenses. 

How Can I configurate zoho for auto posting of my sales and purchasing invoices ? 
Is there any quick way to establish the Financial Statements by recording directly those invoices ? 

Any other tips would be helpful. 

Thanks a lot a have a great day ahead 

Khalid J.