I'm glad you are asking these questions instead of blindly proceeding. Heck, I got nervous just reading your post.

As others stated, first thing to do is confirm the gun is not loaded. Then thoroughly clean it. You do need to resolve the issue at the breech area. Could simply be accumulated fouling and perhaps some rust, but some time and effort will probably cure it. When the gun is clean, put it aside and read the owner's manual. You can probably download one from CVA these days.

Then proceed to the range with proper components. I don't recommend that you improvise patches for sabots, or anything else for that matter, until you have a lot more muzzleloading experience under your belt. I really like Hornady FPB bullets. They are a bore diameter conical so no sabot is needed. They load pretty easily once started, and they are very accurate in my gun.