When working or reading at your desk, a ceiling light is fine for most activities, but when you need a direct or focused stream of light for more accurate detailing of what you are doing, a desk lamp is your best bet. There are a variety of lamp styles, from classic bankers lamps to modern chrome goose neck lamps. There are even touch lamps that turn on with just the touch of your finger. It would be best to consider the size of your desk, how much stuff is on it and what style of lamp would fit best.
Touch desk lamps:
Touch desk lamps pictured:
Left: Ledwholesalers 3 Level Dimmable Dimmable Touch Switch Folding Led Desk Lamp 6 Watt, Pure White, 2403WH
Right: Tayama One Touch Desk Lamp