Install and configure Apache:
https://help.ubuntu.com/lts/serverguide/httpd.htmlInstall any scripting library that you want to use like:
https://help.ubuntu.com/lts/serverguide/php5.htmlInstall a database if your website need it
https://help.ubuntu.com/lts/serverguide/mysql.htmlStart the web-server and databases
Configure your internal firewall if your are using any
Deploy (copy) your website files the web-server root folder, prepare the database if any.
Test your website locally, usually on
http://127.0.0.1/Configure your router/firewall to redirect request to port 80/443 to your PC (where you are installing the web-server)
Get a Dynamic DNS service like
http://www.noip.com/remote-accessConfigure your domain name and ask a fried to access your website