Can I put some descriptions of my company's history on the top of the estimates. I do that in Freshbook, so I wonder I can do that in Quickbooks as well.

Welcome to the Community, @rachel-kim-netki. Yes, you can customize the info to add descriptions to your estimates. 

The sales forms have three sections, the header, table, and footer. Your company info appears in the header, so let's go to the Content section of your template to edit it. Here's how: 

1. Go to the Settings menu, then select Custom Form Styles.
2. Select New Style. 
3. Choose Estimates.
4. In the Content section, select the Header.
5. Enter the descriptions of your company's history in the custom field.

For a more detailed guide, check out Step3: Customize the info on your forms outlined in this article: Customize invoices, estimates, and sales receipts in QuickBooks Online. 

For future reference, read and learn about turning an estimate into an invoice after it's being accepted by the customer. 

Let me know if you have additional questions. We're always delighted to help you some more.