i need a rail gun design for science. im not great with circuitry but i know some. please help me with a simple design?

A rail gun is easier to build then a coilgun just salvage the parts from a microwaves, hook microwave capacitors in parallel and connect the transformer secondary to the capacitors and a switch on the primary. There is your charging system. The barrel is just two pieces of Plexiglas with rails on the side connected two the capacitors. Your projectile nonferric is drawn up the barrel by the current travelling through the rails and it. You insert the projectile into the barrel live so don’t use your hand. There is a lot of arcing so the barrel will need to be rebuilt a lot.
A railgun is just a single discharge system, they arent especially effective and break down quite frequently.
However, a coilgun is the way I'd go, granted, it is a tad more complicated in the controls, but it doesn't break down hardly ever, and takes any size ferromagnetic objects that will fit in the barrel.