help

[ianh]

hi every one, im new to 3d printing, and having a few problems, with what i think is under extrusion. Im trying to calibrate the extruder, and watched you tube videos on the subject, but they keep saying that in one of the lines in ponterface, there will be a line that says somthing like m39 x-y-z-E=what ever number is. but i cant find this line at all. And mine seem to be different to those ive seen on you tube. i have a8 reprap 3d printer which i think is a prusa cheapo version and was wondering if any one could help me. Thank you and look forward to any help at all.