From quotation to order confirmation and delivery note

Open Invoices, choose New document and set Document type to Quotation. Fill in the customer and the lines, then choose Save. A quotation also has a date until which it is valid.
Choose Finalize and then Assign number and lock. The quotation now has its number and is locked.
Send it with Send by email if you want to. A label above the quotation shows where it stands, for example Sent, Accepted or Expired.
When the customer agrees, open the finalized quotation. In the Document chain section choose "Continue as Order confirmation". A new draft opens for you to check and finalize.
From the order confirmation you can continue as a delivery note and then as an invoice. Every step is optional: a quotation can also go straight to an invoice.
Each document lists the one before it under Created from and the one after it under Continued as, so you can always jump back and forth.