Most club flyers are 4-by-6, but you can format your flyers to be any size your heart desires as long as your printer can accommodate the size. Designing them and printing them is a fairly straightforward process once you find the right software for the job.
Open two new files in your desired image design program (such as Photoshop, Illustrator, Quark, or InDesign) and size them to 4 1/2 inches by 6 1/2 inches (this will result in a 4-by-6 club flyer -- the extra half inch is allowing for "bleed, " which is just the edges that can be chopped off during printing if necessary.
Decide on a background color, main photo, and font style for the flyer. Figure out exactly what you want to say on your club flyers. You obviously want to add the where, when, and with whom on the flyer, but you also want to add other other details about the event you are promoting, such as a description of what the guests can expect and contact information. Still, try to keep it simple --- build the entire club flyer around a really outstanding photo that has to do with your event.
Piece together your flyer in your design program; again, the photo should be central with the wording falling into place around the image. Decide what will be on the front versus the back (you can just have a double-sided flyer with the same design if you prefer). The printer should be able to easily cut off the part of your flyer on the 1/4-inch bleed (edges) without affecting important images and text.
Once you finish designing your club flyers, save them as high resolution TIF files. These files are easier for printers to use.
Send your two TIF files to a club flyers printer (see the bottom of this article for a link to a reasonably priced club flyers printer). You should receive your finished flyers within a week or two. If you need your club flyers order in a rush, most reputable printers have that option available as well.