The mechanism of creation manual registration on php. Make the registration form on the main page (index.php) by using the html markup language. Put a link to the php page with the data registration (for example, under the name registration.php). Clicking the "Register" button, the user will be taken to this page where he will have to enter your information in the form fields. Username, password, email address will go to the handler in php. After processing, they will be entered into the database, and check to be completed.
The encrypted password is stored in a mysql database. Create a new table in the database, for example, called usersdata (data users). Create a file bd.php by which there will be a connection to the database. Communication with this file I need to write on the pages before the html code.
Make on the main page (and others) login form with fields for entering a username and password. When the user enters data and presses the "Enter" button, this information will be sent to the file login.php for processing and verification. If everything is correct, it will be stored in cookie. Or will be running the session and data will be stored in the browser until the release or until the browser is closed. For logout from the website will meet file exit.php. When you click on the "Exit" button will end the session, or erased cookie.
If you are not yet strong in the knowledge of programming languages and markup, all you need to do is get ready the code and place it where you want. You can somewhere to take or use the forms designer, such as a service MyTaskHelper.ru. In this case, programming skills are not required. Sign up, create a form with fields you want, give them the desired names, adjust them to your liking. Make the appearance (design) of a form using the module "Widgets". The service itself will generate the form code, copy it to the desired web page.
If you use a CMS (content management system e.g. Joomla) out there for working with forms there are special modules.