How to download IOS 7 for my iphone 5?

Do I plug it into my macbook or just download it from my phone? I'm very confused!

You can either do it from iTunes or from your phone. Updating from your phone is easier though. Just go into your settings, then general, and then software update. Make sure to update over Wi-Fi because it will waste your data and it will be faster. If you update through iTunes, first back up your iPhone, and when it is finished, click on the button that says check for updates and then the download should start. If your phone is filled with too many things, the phone won't update do to lack of memory, and you will have to delete things.

IPhone 5's update will come out on the 20th of september