trimmin and prunin

heya this is my first grow plants bout 3 weeks and round 7-8 inches tall. basically i have no idea wen or how to start prunnin would be worried bout choppin wrong bits or to much any help!!! cheers

There is an entire section on harvesting. Check the forum headers. Here is a link to a sticky for a great tutorial:
https://www.rollitup.org/harvesting-curing/28072-harvest-time-tutorial.html

Hope this helps.