How to add properly a plugin to a theme in WordPress

I have downloaded an existing plugin from the web to use in my theme. How do I add it correctly to the th开发者_运维知识库eme I am developing without using wp-content/plugins folder?

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Depends on the plugin, but you're going to have to extract the functions and add them to your own functions.php file in your theme. http://codex.wordpress.org/Theme_Development#Functions_File

And if the plugin requires css and js files, you need to put them in your theme folder and link to them in your header.php. http://codex.wordpress.org/Theme_Development#Document_Head_.28header.php.29