Hunger mechanics like 1 apple fills up the hunger bar by 1 "pizza" (statbar symbol). Although the statbar show 20 hunger points (10 pizzas) on the HUD you can fill it up to 30 points and apple does not restore Health, but it rises your saturation.
When you start the game you suck at everything. You start with a few torches, some sticks, some wood, and an axe. The tools you make are poor quality and have limited durability. You are clueless when it comes to smelting metals and you ruin most of the lumps you try to smelt. You must mine ores and fight mobs to gain experience. You can use this experience to increase your skills.
Crafting is the way in which blocks and items are made, To crafting, You must move items from inventory into the 3 by 3 crafting grid and then You must arrange the items into the pattern representing the items You wish to create. The horizontal orientation at which the items are placed does matter, except a stairs
Source of Crafting Building and Survival Licensed LGPL v3 :