the easiest way to make a tube-like object is with the Surfaces > Extrude command. Make a path curve, create a profile curve, and then you use that command to extrude a surface along the path in the shape of the profile (a circle in the case of a tube). You'll need to play with the options. I usually put the 2nd and 3rd option to the far right choice in the option box (don't have it in front of me to tell you what those options are exactly).