Google publishers that specialize in erotica (e.g. harlequin press) and send them a manuscript or go through a book agent. Its basically the same as the process for regular books. Or you can self publish.
Most big publishers dont accept unsolicited manuscripts, though, so you would have to find an agent...start by finding agents who specialize in your genre (erotica) and send them manuscripts instead of sending it directly to the publisher because a big publisher will just ignore it.
Most big publishers don't publish explicit erotica at all, so that's not really an issue. To get started, go to online distributors such as Allromanceebooks and Smashwords and look for works similar to what you want to publish. The publisher (although most are self-publishing) will be listed in the book entry. Go to those web sites and check out their submissions guidelines. There are a lot of erotica publishers, so you should be able to find some to submit your works to.
As others have said, have a look at the different publishers and their submission guidelines. I can recommend Fiction4All. Their website looks a little oldschool, but it gets the job done, and they are very helpful if you have any issues.