I repair a lot of cell phones and laptops. The only site I use for tutorials is ifixit.com. They have thousands of guides. You can but parts or tools also. All around the best repair site for any electronic.
I entered all my info and paid for the unlock of a Samsung infuse 4G. I paid at 12:55 am and within 10 hours I had the unlock code emailed back to me. The unlock code worked perfectly and was instant.