I don't think a lot of people get married anymore — kind of an old-fashioned idea when couples can just live together and have kids anyway, if they want. But it's kind of big among soldiers and colonists, just in case something happens to you. You want your benefits and your body to go to your spouse.
If it was me, on Earth ... I don't know. I'm not religious, so it'd probably be a ceremony on my family's farm. We'd put on our dress uniforms, talk about how much we love each other and why we want to get married, then kiss in front of everyone, then we'd have a party where we drink Alenko family wine and lots of beer and we dance all night.
I think I'd want to get married on Earth, now that I think about it.