You need to learn about Copy and Paste In Place and groups/components.
Plus how to constrain to a specific axis.
Here I have selected your line, Edit/Copy, then Ctrl eraser to soften the line. triple click to select all of the ring, right click, make group.
Edit/Paste in Place to put the ring back, draw a circle on the green axis and hold shift to lock it to that axis, position it centered on the line.
Use follow me.
Triple click to select all the new ring, right click Make Group.
Ctrl select to select both groups, right click Outer Shell and both groups become one.
