I assume it's .36 cal; in that case use a .375 round ball with a lubed felt wad between powder and ball (or grease the chamber mouth with crisco or bore butter if not using the wad), 18 to 22 gr by volume fffg real black or Pyrodex P, 15 to 20 gr fffg 777. No more than 25 in any case.
To really do it right you should start at 15 gr fffg, shoot a five shot group, then go up to 17 or 18, do the same, then 20, then 22, then 25. One of those will be a tighter group than the others; that's the load you should use. That's for real black or Pyrodex; reduce by 15% if using 777. Clean barrel with bp solvent between groups and try very hard to be consistent as to how you measure and load every time.
Shot is OK, as long as it's lead shot. However, you will find it pretty inaccurate - close range only.
