What tools do you have?
Simple hacksaw will work, just clamp the bars in a vise and start cutting.
Most people screw up because they try to cut with the same force/speed as cutting through wood and get off track with the cut. Take your time and it will work just fine.
If you have access to a metal cutting chop saw that will be quicker but leaves some nasty burrs behind so you'll need to clean up the end of the tubing with a round file.