Not my stepdad directly, I want my mom to tell him. I'm not sure of their stance on homosexuality, though. And I'm too nervous to ask. And I can't come out with my voice, I'm way too scared. Any alternate methods? Also, how do I get their stance on LGBT people?
You could write a letter or email. I know lots of people have done that--I told my parents and sister directly but emailed the rest of the extended family, and it went just fine. In terms of their stance on LGBT people, you could ask directly, or watch a movie or tv show with an LGBT theme (Modern Family?) and see if it comes up in conversation.
They may not want to watch it on their own, but what if you initiate it? Something like "Hey mom, I heard about this movie/show/whatever. Wanna watch after dinner?" Also, can you think of anything they may have said in the past about LGBT people, either positive or negative?
My parents won't watch TV. Ever. Also, my stepdad has made a few comments to people (racist and anti-LGBT) in the past.
That's unfortunate about your stepdad, but not enough to say for certain he'll react negatively. What about mom?
Nothing anti-LGBT except one time when my uncle got his ears pierced and had earrings. She said "what's he trying to do, look gay?". It wasn't a joke, either.