Direct installation
Single site
Dashboard > Plugins
- Add New
- Search
- Choose install
Multi site
My Sites > Network Admin > Plugins
- Add New
- Search
- Choose install
Download locally
- Find plugins using WordPress.org or from another site.
- Download .zip file to your local machine.
- Use Add New > Upload
Before doing anything take a backup!
If things do go badly wrong see:
Recover from a WordPress Fatal error using your website’s control panel (cpanel)