Instructions
Search the world for resources, such as leather, iron, gold or diamonds. Collect at least seven of a single resource type to craft one pair of pants. To gather leather, approach any cow and hold down your left mouse key to strike the cow until it disappears, leaving behind a leather hide.
Press "I" to open your inventory and click on your mining pick to equip it. Search underground caverns and dungeons for iron, gold or diamond deposits. Approach the target resource block and hold down your left mouse key until the block vanishes to add the resource to your inventory.
Right-click on your furnace to open the smelting window if you have chosen to construct your armor from iron or gold. Drag your iron or gold blocks from your inventory to the top left box of the smelting window.
Add fuel, such as coal, lava, charcoal or wood to the bottom left box of the smelting window to transform your iron or gold blocks to ingots. Click and drag the resulting stack of ingots from the furnace's output box to an empty space in your inventory.
Face your workbench and right-click on it to open your crafting grid. Drag your leather, iron, gold or diamonds from your inventory window to the first, second, third, fourth, sixth, seventh and ninth squares of the grid.
Click and drag the armored pants from the output box of your crafting grid to the third armor slot on the left side of your character portrait in the inventory window to equip them.