Change look of Next/Previous links

I want the “Previous: prev-post title” and “Next: next-post title” to look differently. Something like: “< prev-post title” and “next-post title >”.

I found these posts and my question is: which one would you suggest me to use? And most of all: these suggestions require me to put this code somewhere… but where (and how) do I add that code?

Suggestion 1: https://codex.www.ads-software.com/Next_and_Previous_Links (where the look of the last option before ‘”The next and previous pages” looks like what I want. It’s the code block starting with “<div class navigation>…“)

Suggestion 2: https://www.ads-software.com/support/topic/change-next-previous-post-text/ (where it says, I have to write some function: “wp_post_nav_translate(…”

Help appreciated!

The page I need help with: [log in to see the link]