How to start? This War of Mine Guide

It's good to have everything nearby.

First day you should make feeding your priority, thus crude stove will be required. After getting enough materials (which shouldn't be a problem) you must choose where to locate it. Use mouse, to set it in the right place. It's best when all tools and workshops are close to each other and to crafting station. When the construction is over, you will see an action symbol above the crude stove, which will allow you to use it. Next you should focus on creating a place to sleep, so build some bed. The best choice is a big room, when later you will be able to build three beds. If you still have some time, build a metal workshop and use it to create one or two lock picks. You probably won't have enough materials to make anything else, so the rest will have to wait till next day.