Go to Joomla administration panel and open the settings built-ins. Go to the "Advanced" tab and click "Create". A window will appear "the plugin Manager", where you can select and activate a form of registration. Specify the desired name for the header check the box next to "Show header".
Go to "Initial text" in the form module registration and edit the default text for the visitors if it doesn't suit you. "Login" you can choose how to name the user is on the website: by name or login. Click "Save" for the changes to take effect.
Download Community Builder component on your website. Go to "Upload package file" and click "Browse". After selecting the documents, click on the button "Download and install". Go to admin panel and run the installed component.
Open the tab "Registration" and make any necessary changes to the form of registration. This app is very convenient to use, but if you want to change only one or two fields, it may be easier to edit manually.
Create a backup of the files that you will edit to make adjustments to the form of registration. This will allow you to roll back all actions and to restore the site in case of failure. Determine which field you want to edit or add. For example, you want to add to the form check the City field.
Open the file default.php that is the link components/com_user/views/register/tmpl. Add display of "City" by inserting in the form, check the corresponding HTML code. For this you can copy any other item and edit it under the town (city). Make these changes in the table jos_users. Open the file user.php that is the link libraries/joomla/database/table. Add a new variable. Save the settings and restart the website.