Step 1: Go to Joomla extension manager
From Administrative site, go to Extensions => Manages.
Step 2: Install extension:
Once you go to Extensions Manager, you have three ways to choose from to install your extension. In almost case, you should use the first way, but it is good to know that there are alternatives.
First Way - Upload package file:
This is the most convenient way to upload and install an Joomla extension. Just follow all of the below steps to do this.
Download the extension to your local machine as a zip file package.
From the backend of your Joomla site (administration) select Extensions -> Managers
Click the Choose File button and select the extension package on your local machine.
Click the Upload & Install button.
Note that modules and plugins must be enabled before they will work
Second Way - Install from folder:
This way is suitable for large extesions, these extensions must be uploaded via FTP to a folder in your hosting account since FTP can transfer much bigger files. Just follow the below steps to install extension from folder.
Unzip all of the files locally.
Transfer the files (using FTP) to a folder in the install directory (for example administrator/components/com_installer/components) for the type of extension you are installing.
Use the installer, but select "install from folder" indicating the correct folder name. This folder name should be an absolute path from the root of the file system.
Thirst Way - Install from a URL:
The third way is to install directly through an URL. You need to enter the direct address of the zip archive of the extension you want to install and then click to Install button. The full URL example should be like: http://example.com/your_extensionname.zip
Step 3: Enable and assign the module to specific menu:
From back-end setting panel of your site, go to: Extensions >> Module Manager.
Use the search or filter option to find the new installed module easier.
Enable and set position for the new installed module:
Assign the module to specific menus: