WordPress plugin installation proces is very simple. There are two installation ways: installation via WordPress admin panel, or with FTP (two versions: with your own FTP software or upload plugin .zip file using admin panel). The FTP plugin installation means that you need download plugin zipped files from wordpress site (or other site) to your computer first, and next upload them to plugin directory in your WordPress website. All plugin files contained in one plugin directory (keep the name of this directory unchanged) should be uploaded to plugins folder usually located at (path to your wordpress installation)/wp-content/plugins/. Sometimes, when plugin comes with images or other kind of binary files, FTP software should be set to BINARY MODE for uploading of non-text files. For instance, an image uploaded in FTP text mode would be corrupted. FTP Auto mode sometimes works, and sometimes doesn’t work, so better check in Preferences of your FTP software which file extensions are assumed by FTP as binary and modify the settings. After upload, the new plugin name is visible in WordPress admin panel under Plugins in menu and can be activated.
Easier way of the above option is to use Plugins->Install Plugins->Upload and Browse (for plugin in a .zip format) option in menu of admin panel. In this method you use possibilities of WordPress system which is able to upload .zip file and to install plugin automatically.
The quickest way of a plugin installation is via admin panel, all you need to do is only click plugin installation link. When plugin is installed you have to activate it, usually in Plugins zone in WordPress admin panel.