First check the address at http://cablemover.com and/or https://locator.go2broadband.com to see if there's another cable provider (as in the same technology as us - 75-ohm coaxial to the home) at that address, because if there is, we can't go there unless the city/county kicks them out and invites us in.
If there's not, email us at coxhelp@cox.com with the address and we'll put in a serviceability request. There are a lot of factors that influence whether and when we will move into an area, but that's how we get things rolling.