To create a new quote, you first have to add a job and then create a quote based on this job by clicking on Create > A quote in the job.
Your new quote then appears in the Quotes tab (at the job level). The validity date is calculated based on the validity period you defined in Settings > Accounting. You can update the status of the quote (Created - Sent - Accepted - Rejected) by clicking on it.
When you create a quote, the status of the job automatically changes to On hold, waiting for you to mark the quote as Accepted or Rejected.
When you click on a quote in the list, you arrive in this quote, where you can edit all kinds of things (quote details, notes, terms and the jobs on the quote themselves). You can also generate a PDF of the quote or send it by email by clicking on Actions.