Translations:Survival Guide - Your first day/19/en
From Vintage Story Wiki
Sneak and right click on solid ground with the dry grass in hand to place a fire pit. Next, sneak and right click with 4 firewood in hand to complete the fire pit. Then, light the fire using a firestarter (or a torch), hold 
with either item in hand and aim at the base of the firepit. (Optionally check the handbook H, to find out how to make a firestarter.)
