it is not hard to fix. you can take it to a shop. but you have to learn someday. try going to bethany surf shop first. they can usually help you out.IF NOT, the materials you need are several different grits of sand paper-epoxy resin-fin rope (its like thin strings of glass), gorilla glue, fishing string, epoxy putty (i like epoxy putty, buy it in the boat marine store) OR Q-cell filler, masking tape, spray bottle of water and some latex gloves. use a dust mask in a well vented area. sand all cracks away first and debris. if it is not bad, meaning still attached, just eye it up and and glass it on. dont use to much much material because u will be sanding for a year. just dip the desired length of rip rope into epoxy with harderner alreday mixed in and lay the rope next to the fin where it broke. do a dry run first. then sand heavey grits to fine grit. if it is bad, you can still do it easy. This may require you to remove all excess material (AKA the fin) and sand with a power sander. use a epoxy filler if need be. sand the fin down to untill it is a fin with no chunks on it. make sure it it the same height. next you need to attach a string to the fin that is still attached. take the string in front of the board so it is parralel or flush against the side of the fin. you want to have the string be an extension of your fin. tape the string to your fin and a wall about three feet in front of the nose of your board. now attach a string to the broken off fin so it is the same length. put some gorilla glue ( read directions, you must use a spray of water to activate the glue) on the bottom of the fin. stick the fin on the boards so that the string are parrell (really just going the same direction). both strings should meet together about three feet infront of the board tape the strings to the wall. now you need to hold the fin tight for about ten minutes, then tape it down and continue to eye it up. scrape off extra glua after it dries hard with a stanley knife. glass the fin rope on and your done.sand it away. i made it sound easy because it is. next time get some fin boxes. way way easier.