If you set a concurrency of 192, it means it will try to simulate 192 concurrent users, as in 192 users at any given time. How many total users will be simulated during a certain time period depends heavily on your scenario, rampup time type of sense deployment etc. If your number of sessions was 6912, it means you simulated almost 7000 total user sessions, introducing almost 60 new users per minute. In other words, a very heavy simulation. Considering maybe 10% of a normal user base would active during a hour in a normal install base this would be roughly accurate for a user base of 35000 users. This may or may not be true in your case depending how active your users are.
• You should try to make your scenario as close to how a user would use the app, including simulated think times between the actions (i.e. timerdelay) as no user would click at the insane speed it would mean not to have the "think times".
• Another reason to make your scenario as close to real users as possible is that the load will be close to the real load of users. If you chose actions at random it likely will not be the same load as a real user would cause.
• Concurrent users, mean amount of active users at any given time. Usually maybe 10% of a user base would be active during an hour. This mean if you have a user base of 1000, maybe a 100 users should be simulated during an hour. If your scenario length is 5 min (adjust this to the length of the scenario you created) it means you should have around 9 concurrent users depending on your rampup time.
• Concurrent sessions is much higher than this, depending on the session timeout set in QMC (default 30 min). Running 8 concurrent users with a scenario length of 5 min would have around almost 50 concurrent sessions on the sense side after 30 min.
• Depending on your iterations setting (default to infinite) as soon as one concurrent user is finished, another user will log in and execute a scenario. Instead of a time based scenario you can set iterations. E.g. if you want to simulate 100 users, you can set 10 concurrent users with 10 iterations and execution time -1 (infinite). The time it will take to execute will depend on your scenario length. If your scenario length is 5 min and rampup is 10s, 10 concurrent users for 10 iterations would take ~52min. Execution will exit on whatever comes first, end of iterations or end of time if both are set.
The documentation describes more thoroughly what things mean and how they work.