Most of the mobile artillery was the 6-pound or the 12-pound. I haven't fooled with this stuff in many years but I can give you a quick rundown. Certainly don't try loading a firing any artillery without professional aid.
Clean out the flash hole with the proper tool
The bore is then swabbed to the bottom, usually with a damp ball of wool attached to one end of the ram. This is to quickly clear the barrel of and butt of any residue, especially burning residue.
The load of powder (charge), contained in a cloth bag is then laid in the bore an pushed to the butt (no breach) firmly but not tamped.
If you are using a single ball then it is 3/4 wrapped in a greased lining wad with the bare part facing outward and pushed (very hard) down to set on the charge, and then tamped a couple of good solid thumps.
Move away from the front and side of the piece.
Depending upon the type of fuse used: place the fuse into the flash hole (new ones use percussion caps on a small chain which is jerked sideways to fire). The older models use a short piece of fuse cord pushed firmly into the hole with a twist, leave about 1/4 " sticking out.
Light with a long brand, Repeat process after the recommended cooling time for your piece. Black powder fouls quickly so most folks use Pyrodex, a black powder substitute. You must run a bore hook down it every three or for shots with black powder or you’ll get the ball stuck, very unpleasant to try and get out.
It has been about 30 years since I messed with these and then I was only a gopher, I never actually fired any of them so I could be remembering incorrectly but this is the best I can do.