Open your inventory and look on the right side of it. If nothing is there, press "o". If the menu is set to recipe mode, just click the item to get the recipe or right click to see what that item can be used for. Or press "r" for the recipe and "u" for the uses.
On the bottom of the screen, there's a black bar you can type into to look up items as well.
On the bottom of the screen, there's a black bar you can type into to look up items as well.