Summarize this article in one sentence.
You can access your inventory by opening your Journal and then navigating to the Inventory page.   PC - Press Tab ↹ to open the Journal, and then click the Fist next to your health, magic, and stamina bars.  Xbox 360 - Press B and then use LT/RT to switch between pages until you open the inventory.  PS3 - Press O and then use L1/R1 to switch between pages until you open the inventory. You can drop anything in your inventory on the ground so that it stops weighing you down. Select the item you want to drop and then press the Drop command:    PC - ⇧ Shift+Click the item you want to drop, or drag and drop it out of your Inventory window.  Xbox 360 - Highlight the item you want to drop and press X.  PS3 - Highlight the item you want to drop and press □. Besides dropping an item on the ground, you can drop and immediately grab the item. This will hold the dropped item out in front of you until you release the grab button. Grabbing an item is not the same as using or equipping it, it just lets you move it around in the world.   PC - Click and hold the item you want to drop and grab. Release the left mouse button to drop the item.  Xbox 360 - Highlight the item you want to drop and grab. Press and hold LB. Release LB to drop the item.  PS3 - Highlight the item you want to drop and grab. Press and hold L2. Release L2 to drop the item.

Summary:
Open your inventory. Drop an item on the ground. Drop and grab an item.