From the backend of your Joomla site ( administration ) select installers and then the type of extension ( component, mambot/plugin, module, site template and so on )
* First browse for the package file
* Click the install icon
* Follow instructions
For large extension, you cannot use the automated installer. In such case
* Unzip all the files locally
* In the install directory transfer the files to a folder
* Then use installer to install the file
