It's just like what jupiter said,
You just throw them in the wash or hand wash them yourself. :)
What I do is, I rinse them in cold water first to get the blood mostly out of them, then I hand wash them a little with gentle soap then I throw them in the wash, so's that they don't stain and they stay absorbent.

When you wash them with fabric softener and those little paper things that make clothes smell good, it affects the absorbency. So you do have to be careful of how you're washing them.

@Chexala
That sounds awesome! Where did you get your Diva Cup? I've been very interested in getting a menstrual cup, but I have no idea where to buy it except online. Do you feel it when it's in? That's the thing that I'm most concerned with is being uncomfortable with it...

I could never seem to wear tampons because no matter how I put them in, I always felt uncomfortable. My friends would tell me it's because I have it in wrong, but I've done it a bunch of times, did it exactly how the directions say, I did it exactly how my friends told me to do it, but it still felt uncomfortable.