Use arrow keys to move. Interact the Spacebar, while inventory list is toggled with key I. Hint to press key H. White * is the object that a completely useless to interact with. Green one means you need to use an item with this object to Bain something. Yellow one indicates the thing is an item you can pick up. Red one is a button that you can press to achieve something. Click on a cardboard box at the bottom left of the screen or press Key I to access the inventory. Click on any of the objects in your inventory to use it.