Well, first thing you will need is a loading press. A ponsness warren model 375 is a very nice one. It is a single stage press, very well built and super easy to operate
Another used brand that was cheap and popular was an M E C.
You get a press hopefully it comes with a selection of shot and powder bushing. I have an older Kent brand paper hulled shell that was loaded as a low pressure round and the load it has in it is #5 shot and
30 grams of Tungsten matrix pellets. It is a rolled crimp with a paper over shot card. A system I have no idea how to make. You Tube may be your friend for this.
There may be short plastic hulls. you can use. There is a fellow Wilf Bilozere(sp) who sells specialty shotgun items. he may have every thing you need, including a safe shot to load.
Most products sold for reloading are in groups of 250, for making 10 boxes x 25 shotshells which commonly now refered to as a case of shot shells, or a flat.
Do you have an idea how many shells you think you want to make...?
Best FS