Bilingual

I’m trying to install a bilingual switch between my English and my Spanish pages (already written).
I downloaded the bilingual linker plugin. And follow the following directions to 3. (see below).
I’d really appreciate it if somebody could tell me in plain English what 3 and 4 mean.

Thank you.

https://www.ads-software.com/extend/plugins/bilingual-linker/

1. Download the plugin
2. Upload entire bilingual-linker folder to the /wp-content/plugins/ directory
3. Activate the plugin in the WordPress Admin
4. Add links to posts or pages in the WordPress editor
5. Use the OutputBilingualLink function in the loop to display a link to the item translation.
OutputBilingualLink($post_id, $linktext, $beforelink, $afterlink);
When using in The Loop in any template, you can use $post->ID as the first argument to pass the current post ID being processed.