basically any photocopy place? It depends on what’s cheapest and most accessible in your area tbh. I just print mine at Staples, they have a really handy online submission thing where you can upload your zine as a pdf to their site and specify paper, bleeds, etc, from home, and they have a pretty quick turnaround, plus there’s a staples really close to my place so it’s convenient for me and their rates are okay for colour printing (I do most of my zines in colour). I’ve known a lot of zinesters who worked in copy shops or know someone who works in copy shops and get free printing that way. If you know of a non-profit organization that has a photocopier sometimes you can ask them if you can use it for cheap or free and if your zine ties into their mandate they’ll let you. Or if you work in an office or have a friend who works in an office with a photocopier, sometimes you can stealth-copy your zine there. If you don’t have a free photocopying scheme like that then you’ll want to have a look around and see what place has the best rates, but it’s not that complicated, especially if you’re printing in black and white. You can print up one copy at home if you have a printer and take it in for photocopying, or you can put a pdf file of it on a usb drive and bring it in to whatever copy/print shop you go with and print it from one of their computers. I’m assuming you have it all formatted and ready for print at this point? if not, there are some great tutorials out there on getting your zine ready for printing - if you’re using your computer to do the layout of your zine (like I do) here is a tutorial on making a booklet in InDesign; here’s a photoshop zine tutorial; here’s a tutorial for making a zine out of a single sheet of paper by hand; here’s a tutorial for layout out longer zines by hand.
Good luck and happy zine-making!!