gelly wrote:how do i do that ? sorry i am a total newbie. On the other hand another option is to print really slow i guess
On the process temperature tab there is a check for slowing down on layers that take less than a certain amount of time to print. I've only had marginal success with that though. What usually happens when I slow down is that the hot nozzle re-melts the plastic a layer or two below the current layer and makes the warping worse.
You might try adding a fan. If you don't have one small enough you can put a slightly larger one and just position it further from the printer.
As for the gcode, you'll have to look up what works for your printer and test it out. The spot to add it is on the layer switch tab on the scripts section.