The web server software is an HTTP deamon, httpd. The configuration file for the web server is httpd.conf. The Apache-supplied httpd.conf file is full of comments that explain what each section is for. It's not all that difficult to configure as a local server. Connecting to the internet and actually serving up pages IS more difficult. Making is secure is not a trivial task, either.
The .htaccess file defines rules that grant or limit access to files and directories on the server
So you recommend PHP and will advice building a web page using PHP containing buttons which will communicate to my PC connected to arduino?