You can go to http://www.kobakant.at/DIY/?p=3742 to get the detail instruction.

another tutorial>> http://highlowtech.org/?p=1695

https://github.com/damellis/attiny/archive/master.zip

There are many kinds of ATTINY, but today, we use ATTINY45 or 85

You can also get a USB programmer for ATTINY45/85