Laguna Beach has some nice relatively private areas and it is easy to fly into Orange County airport. Easy for anyone to get to that is flying in from out of town and lots of hotel options. For it to be legal you need to get forms from the county (different for each county) in which you plan to get married and register the marriage. Need recognized officiant and two witnesses to make it legal.
Pick a local officiant and they can help you with the details.
Beach weddings are nice but check the tides on the day planned as at high tide there may be a lot less beach to use. The last hour before sunset is a great time for a ceremony. My photographer, Bruce Stenman at Lightsmith Wedding, checked the tides and the sunset and even how best to have the ceremony oriented for my wedding day next year. A local photographer will know the best spots and can provide advice on parking, getting ready options, and other concerns that you might need even think of in your planning.