To begin with, you need to get your food with a fishing rod and a hook by which you can pick up items.
Then you can kindle a fire on which you can fry fish or cook soup.
With the crafting system to create a new weapons and buildings.
To survive you need a large raft, create it with walls, stairs, roof and also comfort items such as a stove or bed.
You are also waiting for a workbench in which you will learn new things for crafting.