Have some questions to testing.

Right now we are at the production end for first version. So far it was said to use Selenium IDE for Browser side testing, which was barely possible for the size of the website...
Is there other software or are there concepts I can read and inform myself to get into that point to teach myself properly?

The project is a business Website with Work flow system. Php backend and Database with a few procedures and zend framework for browser side.