Please state your problem clearly.
Ideally, you should start by removing the battery & inserting a SIM card. When you turn on the phone you can then register an HPwebOS account which will give you many functions like automatic back up and buying apps. This is the best option unless you have a special use for the device. (e.g. Wifi only or app development)
If you don't have a SIM card, you can put in the number codes to access the device, without using it as a phone. This puts the device into 'Developer mode'. You can them reboot and won't have the start up screen.
If you can not reboot, I suppose the first question is: Is this a new phone or has it been used before?
As GMMan asks, what did you do EXACTLY before the phone would not reboot? It booted once to the 'Create account' screen...
If we know what you did, someone can help. If it is the case that it was nothing you did, then there are ways to recover the phone.