Hello guys i had ask this question already in the past but did not get an answer. So like having a hidden service i heard that you have to change regularly the tor circuit. And my question is is it happening automatically or do have to code a script which do this job? And if yes how?
not necessary unless you are running a large scale market... and by that point you will (hopefully) have the knowledge to pull this off. Look for "So you wanna be a Darknet admin"
You need some IPtable routes and either set up a isolating proxy that routes all traffic of the machine through tor or if you want to be even more secure you set up multiple VMs similar to how whonix works