fireworks and the 4th of july are the number one reason why animal shelters are so busy after the holiday. the sounds cause dogs to runaway in fear. usually these dogs are the poor guys that are left unattended outside in backyards, so as long as measures are taken to avoid that from happening, you should be okay.
sudden noises like the fireworks are pretty normal for your dog to be startled of at first. the important thing to remember is to not tell your dog "it's okay" when it becomes frightened. what you will actually be doing is rewarding them for being afraid and encouraging the repitition of this behavior. the best thing to do is to ignore them when they are frightened and act as if nothing happened. dogs can also sense when their owners are stressed or afraid so it is best to act as calmly as you can in those given situations. let your dog go out and do his business as usual and hopefully he will become desensitized to the fireworks over time.
i would also suggest that you don't let your dog run inside the house in fear after hearing a firecracker. this would be the same as saying, "there, there" as i mentioned above. one option would be to attempt to distract your dog by playing a game that he really enjoys outisde with him when the fireworks are going off. the distraction will hopefully take his attention off the fireworks and onto the game.