Material Gathering

Materials are used to make gear, repair it, and upgrade it.

Woodcutting
Wood is used for repairing and upgrading wood tools/weapons. Use an axe (Wood, stone, iron, diamond) to chop the wood. you will obtain a stick. combine 9 sticks on a craft table to make a plank. Then you can upgrade or repair. Axes can also be used for weapons, since they can be upgraded

Mining
Mining is for Upgrading stronger gear. Again, ore can be mined with a Wood, Stone, Iron or Diamond, but certain ores need better picks to mine

Stone can be mined with any pick. Get 9 small stone to make gravel, then smelt it for cobble. It will repair and upgrade stone tools/weapons.

Iron can be mined with a Stone+ pickaxe. Iron is smelted in a furnace, with wood, or coal, the best fuel item, witch is found in ore. Iron Ingots will make any iron gear.

Diamond can only be mined with an iron or diamond pickaxe. Mining Diamond will give you a "diamond fleck". combine 9 to get a diamond. Diamonds can only repair and upgrade diamond swords right now, but will soon make tools, and maybe armor.

Trivia

 * Diamond tools will soon be added, and maybe armor also.
 * Leather and chain(iron bars) can only be obtained by breaking down the specific armor.
 * Diamond ore isn't in minez 2 yet.
 * Diamonds at the moment can only be obtained by breaking down diamond swords.
 * Unlike other materials, diamond wont stack.