If you receive a Quote Request from a Buyer you will see the details in your Messages with the Buyer.
Click 'Make Offer' in Messages to respond to the Buyer.
Follow the on-screen instructions to make an offer
Hint: The Buyer usually choose Sellers to request quotes based on their listing price. Do keep in mind the price and conditions you offer in your listing for the best chance of them accepting your offer.
Your offer will then be sent to the Buyer for them to accept by paying or decline. You can withdraw your offer at any time and also decline jobs with no penalty.