Change Continue Reading to Sigue leyendo (Spanish)

I am setting up a website for a friend in Spanish country and I want to change the continue reading text in the more link to Spanish. I tried downloading this:

https://siteorigin.com/wp-content/uploads/2014/09/vantage-child-content-single.zip

Then I un-zipped the file on my desktop and opened the content-single.php with a text editor in plain text and edited line 34. Then re-zipped it and and installed it via Appearance > Themes > Add New: Upload Theme.

However it didn’t change anything and when I clicked on the more/continue reading link the page was blank, so I reverted to the original vantage theme.

Any help would be greatly appreciate.

BTW – I Love the this theme.

URL: http://www.pradeltor.com