My dad had one of these when i was a kid, if i remember correctly, at the muzzle end under the barrel is a little round button, if you push this the end should flip up. you can insert a single .177 pellet or something like a dozen bb's, then flick down when loaded, if using bb's you need to have the muzzle point up each time you cock it or it won't repeat. like i said this was when i was a kid they might have changed since then.
They are around £25 new, i have just bought the next one up the G2000 (same just Sliver and black) for £20 posted on here, I think they are good for throwing at a target not shooting, I only want one as this is the first airgun i ever handled and remember being told by my dad DO NOT TOUCH!!! yeah right of course i listened.