Forcing Line Breaks

Hello, I am working with the “yellowflowers-10” theme, and having trouble forcing line breaks in my pages.

Theme:
https://themes.wordpress.net/other/right-sidebar/3807/yellowflowers-10/

I have tried inserting <br /> to add a line break, but after saving, and returning to check the code in the editor, the tags seem to be removed.

I’m sure it’s something simple, but I’m stumped. Just want to add some line breaks, any help appreciated!

– Harvey