How to create Template Overrides using Joomla Template Manager
Since Joomla 3.2 Template Manager you can edit files, create files and folders and even create overrides directly inside your admin area.
One of the useful features of the new Template Manager is how easy it makes overrides. Previously it was almost impossible to get a clear overview of what override possibilities were available on a Joomla site.
Log into the Joomla Administrator(Backend). In the main menu select Extensions → Templates.
You will now see the Template Manager screen. There are two methods available for accessing the Template Manager- Directly - Click the template name in the column Template
- Indirectly - “Styles” will be highlighted, click on Templates below it which will turn the view to Template Manager.
You should now see your template's folder structure, we are going to ignore that though. Click the Create Overrides tab. Select the relevant module, component or layout. Lastly, click the view you need to override.
In the following screenshot, we are creating an override of the Check availability module of Solidres.
That's it. You've just created a template override. This will be used in place of the core file so you won't lose any changes when core files are updated.
To make changes to the new override file. Click the Editor tab, navigate to html/mod_sr_checkavailability/default.php and make any changes you need to right there in the administrator.
Keep in mind that this is a copy of the core file. If you totally mess it up, you can simply delete the file from this directory, and Joomla will go back to using the original core file.
Be careful editing PHP files. Leaving out a semi-colon or closing bracket can completely break your site and leave you with the infamous white screen of death. Backup first.