There is no guide would tell you how to OC a specific model! Guides will only give you the general idea on how to OC models of a specific "series". You won't have any problem in OCing as long as you are willing to read the motherboard manual and understand the guide.
I would highly suggest getting an aftermarket cooler for your processor before attempting to overclock it. Also, your motherboard may not support overclocking at all.
To see, boot up the computer and get to the BIOS screen. There should be information about the processor in there you can tweak. If you have a worthwhile aftermarket cooler, the only thing you shouldn't do is up the v-core, or processor voltage over 1.45 volts.
That guide is a generic guide to overclocking the Core2 chips. All Core2 chips behave the same way. What differs is how the motherboard acts. Some motherboards are great overclockers. For example, a lot of us really like the Gigabyte motherboards. Some models and brands are poor overclockers. ECS generally falls in that category. Unfortunately so do many Intel boards.
Many Intel motherboards, including yours, are designed for stability, not performance. The DG31PR is one of those boards that has what is called a locked BIOS. You have little access to performance enhancing BIOS settings.
Google "DG31PR overclock" to see what I mean. You may get lucky and find someone with a Windows OC utility that will work for you.