Instructions
Press "E" to load the inventory in the game. You will see a gray pop-up menu of boxes filled with items in your possession, such as armor, tools and blocks, to name a few.
Use the mouse pointer to click on an item and move it. Move items from the first three rows to the bottom row to make it easy to access. Each item in the bottom row is accessible by pressing the corresponding number key in-game.
Right-click on stacks of items to split them in half, allowing you to move the other half to another spot in your inventory.
Click outside the window when holding an item to drop it into the game world.
Place a piece of armor in the armor slot in the top left of the inventory to equip it.