Pocket Colt
It is hard for me to get perspective from your pictures, but I suspect you have semi- replica of an 1862 Pocket Navy. I say semi as the the original frames were steel and your repro has a brass frame, which is a common thing in replica C&B revolvers.
You state the caliber may be .30, if that is the case then your copy MAY be an 1849 Pocket that came in .31 caliber (kind of). If it is a .36 caliber, it it a Pocket Navy (again sort of). I state "sort of" as the .31's take .320-323 balls and the .36's take .375-380). The 1849-.31's are really tiny, so I think your gun is actually a Pocket Navy in .36.
As in all things these days, I suggest checking on Youtube on some tutorials on how to load and fire a C&B revolver. Watch several. It is imperative you use black powder or a black powder substitute like Pyrodex. In brief, loose powder is poured in the chamber mouth, using a powder measure for a specified amount. A lead ball is placed in the mouth of the chamber, then the rammer on the pistol is used to drive the ball down into the cylinder. Grease/lube is then smeared over the mouth of the charged cylinder. Once the cylinders are charged/greased, percussion caps are placed over the cones on the back side of the cylinder. A tool known as a "capper" helps in this process, but is not essential. There are a number of nuances to this process, watch the video's, "duelist1954" does a good job with his material. If you could locate an experienced C&B shooter, that would be beneficial, but not essential if you are familiar with firearms to some degree.
The brass framed guns are thought to be a bit soft by many. If your gun is indeed a .36, I'd think a charge of 15 grains would be appropriate.
Black powder is corrosive, a good clean up after shooting for storage is essential.