Hi, may I know how do I create the Sweeping surface along the vertical interior cylinder? I created a Helix but I'm not sure how should I proceed next
After the creating the helical curve, sketch a rectangle on a plane normal to the helix, preferably at the starting point. Sweep this rectangle along the curve and you will have your screw thread surface.
If you need advanced help on sweeping zero thickness surfaces leave a comment.
Answered with a tutorial: https://grabcad.com/tutorials/how-to-create-helical-model