My shorkie barks at anyone who he sees and runs up to them and starts barking and won't stop. When we're in the car and people come up to the window he freaks out and growls and try's to attack them. How do I get him to stop doing this?

You own a terrier. Terriers are very protective and barky. Its just who they are.

Introduce the command "leave it".. Start with various objects. When you say "leave it", that object can never be given to the dog. It is completely off limits. Once he starts responding to this command, start using it for when he barks at people.

I'm not a fan of squirt bottles, I think it creates a head shy dog.. But a lot of people like to use them. When he starts to bark, squirt him in the face and say "no" very firmly. And continue to do this until he starts to listen to you. Like I said, I don't like this method, it's a crutch, it never really solves the underlying problem. Which is why I suggested the "leave it" command.

I attached a YouTube video on how to teach the "leave it" command. It's a very simple command, but very useful!

http://www.youtube.com/watch?v=bIESS2MK4aw

I'm afraid I have the adult version of your pup without the growling towards people, only other dogs. A 10 pound feisty little poodle mix who loves to not only be seen but heard. After trying to correct the behavior I decided that this is simply the way she is. She is still a lovely little dog.
Yorkies, by nature a owner protective breed.
I'm certainly not suggesting not to take Luckys' good advice, just that it may be something you have to live with.

Hi Have you ever tried obeideince training. You may find that if you start training him with treats now that you will have an obedient adult dog. Check out the traing advice at shorkietalk.com. I am amember there we talk about all sorts of topic's and help each other out. Would love to see you join us.
Take Care
Ann

When he barks don't yell at him it just sounds like you are barking along with them.shorkies are very protective and will warm you about everyone it is just their nature.as ann has stated obedience training can help.you could get an anti bark collar they cost about 50 pond brand new.training him and keeping him on a leash can stop him running up to people and barking.