That reminds me of a local boy who posted on a BBS that he had bought a keyboard vacuum and the first time he used it he cut his lip. I didn't know what to tell him either....
Well, you understand you have to hold onto the knife with one hand and pull on the ring with the other and that will unlock it and the blade will be free to close, right? I suggest you do it slowly, and think about it. Take a grip on the knife and think about whether that's the grip you want to have when the blade closes. If not try a different grip.
People have been using ring locks for around 2,000 years, but there don't seem to be any written instructions available....