From the tiny settlement of Brighthelmstone, Brighton was formed. In the 18th century, the south coast grew in popularity as a healthy place to visit. I wonder what your ancestors thought of it all! Even if you cannot ask them, you can certainly trace their movements through their baptisms, marriages and burials recorded in the Parish Registers.
More parish register transcriptions on fiche and/or booklets can be found on the relevant family history society pages.