Now what do you do once you have passed? LOL

Congrats. That's terrible that you're on your own figuring out how to proceed. All you have right now is national certification. You will receive a certificate from whichever board you took the exam from. The next step is to apply for state certification with your BON (granted you do not live in CA, KS, IN where in some situations, national certification is not required). Sending proof of national certification to your state will require an additional fee that is going to be charged to you by the national board you got certified from.

Does your state require additional documents and proof of competence prior to being able to prescribe? Some states do and this is something that is quite variable and specific.

You should apply for a job now. You employer will hopefully guide you in whatever you will need next. You can get an NPI number on your own via https://nppes.cms.hhs.gov/NPPES/StaticForward.do?forward=static.npistart.

In some states, you can already apply for a DEA on your own. Some require documents (such as a collaborative agreement) which you will not have until you're employed. The website is DEA Diversion Control Program Registration Applications. I personally would wait on this especially since many employers are willing to pay for the fee.

Well, the first thing you do is celebrate! You've worked hard and should acknowledge your success. Juan gives excellent advice. The only other thing I would check is the necessity for a separate controlled substance registration in your state. In my state I have to have my state license, my DEA registration, and my state controlled substance registration. My employer pays for all of that, so it might be best to get your state license and hold off on the others until you get a job.