Uwhoosh on "[Theme: Celestial - Lite] Post Excerpt"

First, thanks for the great theme. Installed it and with some modifications, I'm loving it. One thing though, I have a blog and I tend to write really long posts. So I’d like to have post excerpts on the blog's landing page. Tried to find that option on this theme to no avail. Tried to edit the index.php, change the the_content to the_excerpt, no luck. Stumped. Any suggestions?
Thanks.