how could I add my number on my selling page

Unfortunately, it is our policy that every first interaction between buyer and seller through CarGurus is over the email accounts registered on the site. This is to protect user's personal information as well as allow us to track the interactions between users and maximize our user experience. Because of this, we do not allow phone numbers to be listed on our site. I am sorry for any inconvenience this may have caused. However, once a shopper reaches out through the messaging platform, you will be able to exchange contact information there.