How to make a dimmer for a 11W CFL?
Before you do anything else, stop and read the fine print on the side of that CFL's base. Do you find the word "dimmable" there? If you don't, then you're begging for real trouble if you try to dim it electronically. An ordinary CFL represents a capacitive load at the moment of turn-on, meaning it draws a LOT of current before it's lit and the mercury inside warmed up. If you dim that bulb by any conventional means, then 100-120 (country-dependent) times per second that CFL will go through a start-up moment, during which it draws very high current. The result: greatly shortened lifespan, excessive heat, possibly even a fire.

The best way to accomplish what you're trying to accomplish is to build a hardware shade that can be adjusted for brightness. You can come up with a clever design, I have faith in that.