Google books on identifying edible seaweeds or go to your local library or bookstore and pick up some books, you can also see if there is someone who sells locally harvested seaweed and see if they can be a resource for learning to identify and harvest your own. There are edibles you can harvest from the shore and others you will need a boat, and you can dry them by hanging them outside in a dry sunny location of inside in front of a fan. It is perfectly fine to harvest yourself if you feel like you can make a positive identification, I have had friends harvest dulse and other seaweeds off the coast up here in the Pacific Northwest, they went with a local herbalism school, perhaps there is one of those where you are located?
