There are some things that need to be crafted when you first start out to help you defend yourself and also help in the building process of your structures. This is your priority to build the shelter once your game starts.
Once you get the shelter built, you can then save your game and sleep at night to get away from the cannibals. Once your trees are chopped down, pick up the logs and use them to build your shelter. Once the plans are down and it is in the place you want it, go and chop down some trees and find some sticks. You have to place down the plans on the ground first before adding anything to it. The building is very different from other games because you must carry the materials from the ground to where you are building your structure.
The first thing you have to do when you gather all the material from the crashed plane is to go and build a temporary shelter somewhere close where you have a safe place to stay at night. Find a good area to build a more permanent base.