Are you saying this functionality is not built into Fictive, and that I have to change the code?
There are two ways to display excerpts in Fictive. You could add the More tag manually in each post where you want to break it:
(This guide is from WordPress.com but the tag is the same for self-hosted.)
Alternatively, you could create a child theme and change the code so that excerpts are displayed on the homepage automatically.
Both routes will work, but the child theme route means you won't need to manually add the tag. The child theme route also lets you use manual excerpts, if you prefer to craft custom excerpts for any posts.
I am very squeamish about getting into that and have no idea what a child theme is, etc. Perhaps I need to select a new theme?
Child themes are fairly simple to set up but if you're not comfortable at all touching your code you may be better of with a theme that displays excerpts by default.
If you have any other questions about Fictive, please start a new thread, thanks!