@williamatics Sometimes trying to join pieces makes more problems than having them separated. If you want to join them select both and press ctrl+j. You will have to delete the vertices that end hidden and then manually move them so it ends with edges where the pieces meet. For the round pieces, you can use the method in the Airplane course, you have to select the rail, put your view in orthographic, to the side, spawn a circle with the same amount of vertices than the cylinder, align it to view, use “project from view” if needed. Then you will have accommodate the vertices of the rail to the circle.
