You can find out about anthology calls from a variety of sources. If you have a particular press in mind, follow them on social media and keep an eye on their website’s submissions page. If you are open to anything, there are websites such as New Pages, where publishers list their calls. Finally, check out a few of the groups on Facebook. I belong to several where people add details for any new submission calls they come across.
Once you’ve found a call that interests you, check out the details. The information should tell you the theme for the call, and any other requirements such as word count and closing date. It should also mention the remuneration. Some publishers pay a one-off fee for a short story. Others offer a shared percentage of any royalties. There are also some who only offer a copy of the publication as payment. I personally prefer to receive some form of monetary recompense, even if it’s only small; however, that’s a choice you need to make for yourself.
Whatever the case, but especially if there is no payment involved, take a good look at the terms of the contract. Any reputable company should be willing to share this information before you sign with them. Check whether they are asking for exclusive rights, and when those rights will expire. If it’s non-paying, I would not expect the rights to be exclusive, leaving you free to reuse the story elsewhere after initial publication. Whenever you sign a contract, ensure you fully understand the terms, and seek professional guidance if necessary.
At this point, if you feel happy to go ahead but aren’t familiar with the publisher’s work, it is worth taking a look at one or two of their releases, to give you an idea of their preferences in terms of style and content. If what you are writing is vastly different from the other works you see coming out from them, it may not be a good fit, and you’d be better off looking elsewhere.
Although many calls are specific, requiring you to write on certain topics or themes, if you have ideas and time to spare it’s always worth penning a few stories to keep in reserve. So long as they aren’t too out-there, a suitable call is likely to come up at some point, and you will then have a story essentially ready to go, perhaps only needing a few tweaks here and there.
In all respects, getting a few published short stories under your belt is an excellent springboard to start you on your career as an author.