This article introduces briefly how to install an extension in LibreOffice. It is very easy in only 3 steps. We choose MultiSave extension as example here. It is an extension to save document into many formats simultaneously. You may apply this example for another extensions. We hope this will be useful.
Download Extension
Go to http://extensions.libreoffice.org/extension-center and find one extension. Download it. For example, we find MultiSave is interesting and we download it from http://extensions.libreoffice.org/extension-center/multisave page. The direct link URL is http://extensions.libreoffice.org/extension-center/multisave/releases/1.3/starxpert_multisave-1.3.0.oxt. Remember that the file extension is .oxt.
Open LibreOffice Extension Manager
Open your LibreOffice. Open menu Tools > Extension Manager.
Install The Extension
In the Extension Manager window, press Add button > select the .oxt file you just downloaded. Optionally you may restart your LibreOffice to make sure it enabled.
Use The Extension
For this example, we installed MultiSave extension, we find its icon in Writer's toolbar. For another extension, follow its documentation or just find it manually. This is the screenshot from MultiSave dialog.
Reference
https://wiki.documentfoundation.org/Documentation/HowTo/install_extension