how do i build a hut

You mean build a shelter or hut? Cause to be able to build a hut comes much later into the game.To build a shelter, you muz get you're mechanical skills up to level 5..in order to up your mechanical skills you have to harvest stuff, climb trees or craft things..

Climbing trees is for body. And if ure talking about the shelter thing, I unlocked all the crap just outta nowhere [forgot how it was a long time ago] and it gives you different #s of walls you can use [1,3,5,7 I think] and click on them, or on the first page [of shelter plans] it has walls and roofs premade, click on it and find flat ground to put it on, I vote beaches personally. But after ure done placing it and ure back on game mode ure sims hasta contruct it now. Good luck.

Just craft it in the working bench...

Ermm you don't craft it in the working bench