Installing a plugin is much like installating a module, the steps will seem very similar.

Step 1:

Download the plugin to your desktop.

Step 2:

Log into your Joomla 2.5 Dashboard.

Step 3:

In the top menu, hover over Extensions and then click Extension Manager

Step 4:

Under Upload Package File, click browse and select the plugin you downloaded in step 1, then click Upload & Install

Step 5:

After installing plugin successful, in the top menu, hover over Extensions and click Plugin Manager

Step 6:

Use the Filter feature to find your plugin, and then click on the plugin in the list below

Step 7:

Configure any settings specific for this plugin

Step 8:

Click Save & Close