Step by step guide for benchmarking PHP project

Can anyone guide me how to load test/benchmark a project written in plain procedural PHP (no framework) and MySQL to identify the bottleneck ?

The project uses SESSION开发者_运维百科 to store some values.

I've the last version of WAMP !

[On SO i found JMeter to do the job, but there was no step by step guide, neither i found it on the JMeter's site. Looking for help from you.]

If you want to profile your code to find out, which part of it takes all the time, you're looking for a profiler.
With WAMP, I'd recommend the xdebug profiler with webgrind to visualilze the data.

On the other hand, if you want to know, how much your site can take, you should take a look at Apachebench, which should come with WAMP.
You didn't specify, how complex your benchmarking needs are, but apachebench should make it possible.

Use PHPUnit for testing:

http://jsdoodnauth.wordpress.com/2008/11/05/installing-wamp-and-phpunit-on-windows/

Unit Test based development.

This allows you to produce bug free code. It also benchmarks for time.

And PHPUnit definitely is the way to go