Getting your transcript. First that's what you'll need to finish any kind of ged, or get a diploma. How to get your transcript is quite easy. Call your high school, ask for a guidance counselor. Give them your name and maybe the years you attended. Now chances are they probably won't mail it to you directly, but they will mail it to whatever program you decide to finish with. Maybe you have to pay a small fee even. If your school closed down, then call the department of education.
Choose where to go. If you are on the phone with the counselor, about this transcript, maybe you ask their opinion. He or she will give you probably some phone numbers, and help point you in the right direction. Or maybe someone to talk to specifically that can be more of a help. Maybe some nice school programs in your area. The actual school itself may carry it, some might not. My local high school didn't, but I used to go to take night classes at another one. The counselor will know and be helpful.
Finishing your education online. I'm not real crazy about this, because there's quite a few programs, although they may appear decent, I'm not sure you get actual credits for them. Some college might not accept these. I'm not suggesting there's none that aren't legit, there's only one I've found for sure and I'll list that in my next step. Except it's not really online, but it's independent. Something to do on your own time. Whatever you do, research online when it comes to high school programs. E-mail some colleges or something you might want to attend, and see if they'd accept credits from these programs.
Join american school. This is a home school program, that you do on your own. It's kind of pricey, depends how many credits you need. They have instructors that can help you, though. The price range is from around 500, to 1000 I believe. Yeah, I know, not cheap. Whatever you choose will cost some money, even night school isn't extremely cheap. You must complete at least 4.5 credits to get a diploma from them. They are legit and you'll get accredited. They've been around since 1897, they're no joke. You can take two different programs. General High school course, and Preparatory College course. I'd take the second one, if you want to get into college. Do your research on them. If you don't have time for night class, and want to go to college, save up and join with them. There's 70 subjects you can study in. Click on the link on the bottom.