I can't answer your question directly because I've never used EasyPHP (I've always advocated manually installing PHP, Apache, and MySQL using the installer packages from their respective websites).
I can, however, tell you that there should be a "php.ini" file in your PHP directory; if not, then you must rename one (probably the recommended one) and go through it to ensure that the paths/options are set as you would like. If you need help figuring out what one of the directives in that file mean, take a look at the appedix in the PHP manual for the list of PHP directives.
I would assume that this installation is simply a development server and not a production server, correct? If so, you can go ahead and make sure display_errors is set to On and error_reporting to E_ALL | E_STRICT to ensure that you can see all errors while developing your applications. Also note that register_globals and magic_quotes_gpc should be off.