Hello, I was starting my new mac book air, and fill it out with all my apple informations the screen became dark with a symbol similar to a stop sign, what should i do?

Hey Eduardo,

I am sorry to hear you are having an issue with your new MacBook Air, that must be very frustrating. Let's see if we can get you back up and running.

If you are seeing a prohibitory symbol on your screen, it is likely that your startup drive needs to be repaired, or OS X may need to be reinstalled. Follow the steps in this article -

A flashing question mark or globe appears when you start your Mac - Apple Support

Specifically -

If your installation of OS X needs repair

If you don't see your startup disk displayed in Startup Manager, or if you see a prohibitory symbol (⊘) appear, your startup drive may need directory repair, or OS X may need to be reinstalled.

1. If you only see a disk named "Recovery HD" in Startup Manager, select it instead. You can also start from OS X Recovery by holding down Command and R on the keyboard at startup.
2. From the Utilities menu, choose Disk Utility.
3. In the Disk Utility window that appears, select your startup disk (usually named "Macintosh HD") from the left side of the Disk Utility window.
4. Click the First Aid tab.
5. Click Repair Disk to verify and repair any issues with your OS X startup disk.
6. After repairing the disk, try to start up normally.
7. If none of these steps resolve the issue, start from OS X Recovery and reinstall OS X.

Thanks for using Apple Support Communities.

Be well,

Brett L