Have you done the Help>Tutorials?
A Sweep feature requires two sketches.
One sketch for your bent tube path and a second sketch for the tube profile.
Project Geometry and select the Origin Center point from the browser. Sketch a horizontal line from the projected origin to the right and then hold down the mouse button on the end of the line and drag out an arc from the line.
Click Return to exit sketh mode.
Rotate your view around just a bit and start a new sketch on the origin plane perpendicular to the line of your first sketch.
Project Geometry the Origin Center Point from the browser again and then sketch two circles at the projected origin (end of your line path). Click Return and select Sweep.
All of this is covered in the Help files and any level 1 class.
As you progress you might want to do the tutorials on Frame Generator as well.
Once you get the basics you might want to investigate complex 3D sketch paths. Here is one I found
