[eluser]jalalski[/eluser]
You can have as many classes defined as you like. But...
You would normally load a library like this (in a controller for instance):
Code:
$this->load->library('testcenter');
$this->testcenter->dosomething();
In this scenario, the load function is looking for a file called testcenter.php and then looking inside for the class by the same name and instantiating it. However, you would also be able to do this:
Code:
$this->load->library('testcenter');
$t = new Test();
$t->addTest();
Take a look in the manual for the section called "Creating your own Libraries" for more details on naming and such.