Read More Customization

Hello..
I love this theme, but I’m sad I can’t change the ‘Read More’ to my own custom text (individual posts). :<

I know nothing about coding, do I need to edit the index.php file?

related article:
http://codex.ww.wp.xz.cn/Customizing_the_Read_More#Having_a_custom_text_for_each_post

Thank you.
Masova