Where to find Spanish .mo and .po files (es_ES.mo, es_ES.po)

I have been tasked with building a multi-language site, in English and Spanish. I am using the WPML plugin, and it’s working beautifully, except for one thing. When one toggles to the Spanish language posts and pages, the navigation for “Home” does not translate. The WPML forum suggests installing the .mo and .po files and editing the wp-config.php file, but I have absolutely no idea where to acquire the es_ES.mo and es_ES.po files. The WP Codex points to the WP in your own language documentation, but unfortunately I am not familiar with enough with Spanish to be able to understand the documentation.

I tried downloading WP from the from the es.www.remarpro.com site, to see if perhaps they were a part of the download, but I could only locate mo.php and po.php files.

I have a feeling that there is something very basic about this that I just am not understanding. Any guidance, suggestions or help would be greatly appreciated.