You will need to gather many items throughout your adventures in Sarnaut! Many quests require you to collect items from your surrounding environment, and in some professions such as herbalism you will need to gather crafting materials such as plants. To help you find gatherable items, you can make them light up by pressing "T". Once you find a gatherable item you can gather it by simply right-clicking on it.
You will also need to gather items that drop from NPCs that you have defeated. To gather the items you can right-click on the bag that appears near their corpse and then left-click on the items that appear. To successfully gather any items you must have open space in your bag.