Finding parts for high power LED

I need help finding a MOSFET for this LED.
http://www.ebay.com/itm/EPISTAR-20W-Super-Actinic-Blue-Hybrid-Led-Panel-Aquarium-/220990452654?_trksid=p4340.m1850&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D11%26meid%3D813608878417348804%26pid%3D100011%26prg%3D1005%26rk%3D1%26

Also when using a MOSFET to dim do you need a dimmable driver? Won't the MOSFET go on the power from the driver to the LED? And also is there anything I should put inplace in-between the PWM and the MOSFET?

Search Results for mosfet - SparkFun Electronics COM-10213.

Also when using a MOSFET to dim do you need a dimmable driver?

No, you don't. Base on information on web-page, my guess there are 9 leds configured in 3 strings with 3 leds each, so power already optimized to +12V source.

Won't the MOSFET go on the power from the driver to the LED?

What is that means?

And also is there anything I should put inplace in-between the PWM and the MOSFET?

Resistor 120 - 200 Ohm.

Magician:

Won't the MOSFET go on the power from the driver to the LED?

What is that means?

Right. Thats not really clear is it. How would I wire the MOSFET chip into this setup? And also this is my first arduino project so bare with me and thank you for the help. What MOSFET model would you use?

Click on a link in my response (first line). Than click on a product picture, referenced COM-###### on SFE website (my search results shows it on the left, your could be different). Than click on a link #3 in Documents. Hope, you will get to the tutorials:
http://bildr.org/2012/03/rfp30n06le-arduino/ Though this guy don't use a resistor in series with arduino pin, which isn't quite correct but may be acceptable for short period of time if you don't have a resistor around.

Very clear now. Thank you for your help in sorting this out. Before I start placing orders for the resistor and the diode (I have nothing like this and there is no store near me that would) is there a good/simple starter kit that someone could suggest?

"good/simple" depends on your intentions, for now we only know than you lighting up a led. What else you will be interesting in, music, lighting, robots, weather observation? Probably, you better look around with google "arduino kit", or check sparkfun :
http://www.sparkfun.com/search/results?term=kit&what=products
Read what included, what projects you can master, and if there is a question, than you post specific question, "is a better option for kit-number/link" etc.

The only parts I have are the arduino, led and driver at this point. I'm wanting to dim the LED and use a "thunder storm" mode which just flashes randomly at night. I found and ordered this.
http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=200794542197&ssPageName=ADME:L:OU:US:3160
I probably paid to much but its to start me out. After this project I will be able to know what parts I need and hunt them online. The only other thing I need now is the MOSFET chip.

After I get this down I will work on the auto top off water pump for my reef tank. Then wave makers. Then temp control. And add on from there. Does anyone know any fellow reefers that use this forum? I've found many on reef forums who use the arduino but I don't want to join each forum just to talk to one person. I'm sure there on here somewhere. I'll try searching. But if you read this and think of someone off the top of your head please link. Many thanks.

Magician:
Click on a link in my response (first line). Than click on a product picture, referenced COM-###### on SFE website (my search results shows it on the left, your could be different). Than click on a link #3 in Documents. Hope, you will get to the tutorials:
http://bildr.org/2012/03/rfp30n06le-arduino/ Though this guy don't use a resistor in series with arduino pin, which isn't quite correct but may be acceptable for short period of time if you don't have a resistor around.

Which Pin are you talking about here? I have 220k and 10k

Look at the picture: http://bildr.org/blog/wp-content/uploads/2012/03/rfp30n06le-arduino-solenoid.png
Pin 3 connected to resistor and gate of MOSFET transistor. You need one more resistor 100-220 OHm in series with the gate( green wire).

Magician:
Look at the picture: http://bildr.org/blog/wp-content/uploads/2012/03/rfp30n06le-arduino-solenoid.png
Pin 3 connected to resistor and gate of MOSFET transistor. You need one more resistor 100-220 OHm in series with the gate( green wire).

Awsome. Very clear. So would this explain wh ymy computer freaks when I connect to my arduino via usb and the power supply to my LED is on?