Welcome to the forum.
Your pistols can be loaded with real black powder or any of the granular synthetic black powders like Pyrodex, Seven7seven, Shockie's Gold or similar. Some work better than others and real black powder works best.
Under NO condition should you ever load any smokeless powder of any kind.
The guns usually shoot round lead balls best and these are loaded without a patch of any kind.
If your using a .451, .453 or .457 diameter ball none of them will fit freely into the chambers.
After loading the powder charge, the ball is forced down into the chamber by the loading lever.
This should shear a circular ring of lead off of the outside of the ball where it meets the chamber.
If properly swaged, the ball will seal the chamber mouth and those in the adjacent chamber should stay in place while the gun is being fired.
Some folks like to use lubricated fiber wads between the powder and the bottom of the ball. This both lubricates the bore and serves to prevent flames from the chamber being fired from sneaking past a ball in an adjacent chamber and causing it to fire. (chain fire)
Your gun will probably work with either #10 or #11 percussion caps.
With a steel framed revolver you cannot accedently over load it because the chamber will only hold a safe amount of powder.
When loading the powder, leave about 1 balls diameter of room above the powder charge for the ball.
If your pistols have a brass frame (the part that the cylinder rests against or in) you should reduce the powder charge.
Although brass framed pistols are safe to shoot the power of a full powder charge can damage the frame over a period of time.
Most C&B revolver shooters find that a smaller than 'full' load produces the best accuracy.
Although the chamber will hold more, a powder charge of around 25 grains works well in a .44 caliber pistol.
One thing to pay particular attention to when shooting is the caps on the loaded chambers.
They must stay in place at all times until they are fired.
If a cap falls off of the nipple when another chamber is fired, the flames from the rear of the firing chamber can find its way thru the nipple hole. If this happens, that chamber will also fire.
Have fun.