Lack of confidence is normal in the beginning even more so if you have never ridden before. A good habit to get into is doing your pre ride checks, so check things like oil and water, lights, tyre pressures and condition etc. Doing this will calm your nerves as you are not rushing to get out on the bike just take your time, it is not a race. Secondly it will help build trust in the bike as you know it is safe to ride.
Like most things it will take a good few miles under your belt, just take it slow and steady find some quiet roads, go to some retail or industrial parks when they are closed and practice the slow maneuvers you did on the CBT, all this will help build up muscle memory for your clutch and brake control.
Good luck and keep at it