A 6 cm wheel controls the head clamping and is tightend with right hand.
The brass circular device is the place the auto focus cam rides to adjust the lens up and down (focus). The cam is not circular.
The focus is set with the enlarger at full height and the column height set to the thickness of the easel. Crank on top the column to set easel height. After that, focus is automatic.
Set the top ring tight to the right. set the lower ring to achieve focus, the tighten the small thumb screw. Once this is tight, there is a detent so the focus stays there but can be forced out if you change carriers or work outside the AF range, but you can return to it easily.
There is a good chance the f stop on the lens will not be centered. Then loosen the thumbscrew, rotate the lens, then readjust the the ring with the thumb screw to reachieve focus. Repeat as necessary to get the lens window facing you and the image in focus. Tighten the small thumbscrew to reestablish the detent.
A better picture would really help.
Be sure to set the column height to the easel paper surface height above the baseboard or the auto focus will not work.