How to create custmers database on my accounting then create estimate and send .when customer approve convert to invoice and get paid?

Thanks for connecting with us here in the Community, dariusz-dem-gmai.

I'm happy to guide you today so you'll be able to create an estimate in QuickBooks Online. 

Here's how :

1. Select + New.
2. Select Estimate.
3. Select a customer from the Customer dropdown.
4. If the work has already started, select a status from the Pending dropdown. This is optional.
5. Set the Estimate Date and the Expiration Date.
6. Enter the products and services you plan to sell.
7. Enter any other info you need.
8. When you're ready, select Save and send.

To know more about the detailed steps you can check out this article: Create and send estimates in QuickBooks Online.

After customers accept your estimates, you can turn them into an invoice and request partial payments. 

I've got you an article to guide you in Customise invoices, estimates, and sales receipts in QuickBooks Online.

Keep your post coming if you need more help. I'll be here!

@dariusz-dem-gmai 

QBSE doesn't provide Estimate feature. Consider switching to QBO.

https://quickbooks.grsm.io/UK