This is a good place to look for CPU specs: CPU-World
You need to find the specific CPU type looking at the CPU's manual or on the CPU itself
(Before connecting the CPU fan).
For example, check this picture of CPU from Wikipedia:
You can see this CPU's spec here: CPU-World - Intel i7 - 2600k 3.40GHZ
Just search for the model in the site.
If you want to compare performance of different CPUs, try Tom's hardware, they are the best at comparisons and reviews.
I thought you wanted to know where to see and compare the specifications of different CPUs, If you want to learn details about what each specification means, you can check this out:
Hardware-Revolution - 12 CPU Specifications Explained in Plain English
You are welcome to ask for more details if you want.