Without knowing whether it is a Colt or Remington type revolver, it's a little tricky to know what size ball you'll need, but .454" is a safe bet. You want a nice, even ring of lead shaved off the ball when you seat it and you want the ball seated on the powder charge--no air space. Say 25 or 30 grains of FFFg or the equivalent. The ball should sit even with the chamber mouth and not protrude past it. Lube the arbor--the axle the cylinder turns on before you load, and after you load you can put some lube over the ball if you want. It keeps fouling soft, but if you use the right size balls you don't need to worry about a chain fire from the cylinder's front. And if you use a ball that is too small, all the lube in the world won't stop a flash off. Make sure you have the proper size caps and that they are firmly seated on the nipples. Because loose caps or caps that fall off are the cause of chain fires. You are now ready to shoot.
Some like to shoot squib loads in their revolvers when target shooting and use breakfast cereals to make up the difference--Cream of Wheat for example. I suggest you get some experience shooting the gun the way the old timers did before you try this.