A lot of us use those adjustable desk lamps, but if you're stuck for space, I recommend this LED desk lamp:
[URL unfurl="true"]https://the-gadgeteer.com/2014/08/13/taotronics-elune-dimmable-led-desk-lamp-review/[/URL]
That was just a convenient link to show the lamp, but you can find it from many different vendors, online and at brick-and-mortar stores. I got mine for around $28 off Amazon.
I bought one to keep in my traveling tool kit, because it breaks down into a very small package, but I'm using it now as I paint at the kitchen table. It has three brightness settings, and can be focused very easily.
I wound up buying myself a second one for my desk at work; I shared an office with two other guys who always wanted the ceiling light off, and I needed more ambient light around my monitor.