add "read more" to a widget

I know this has been discussed before, but I can’t find an answer that seems to work for me.

I’m using the ZeeNoble child theme. I have put some text in the columns created by the Frontpage Widgets #1. What I can’t figure out is how to add “read more”, to cut the length of the text (say, after the first paragraph) and allow readers to access the rest if they choose. I’m hoping this can be done without going into the code because I’m not really comfortable with that. There are some plugins but none that appear to be OK with the latest version of WP. So…any help much appreciated.

thanks
john