Notes out of scale

How do I use the notes out of the scale ?

Like this tab below on V/V chord:

https://www.hooktheory.com/theorytab/view/queen/we-are-the-champions

Sorry for my english.
Tks.

Select a note, then press the “<” or “>” key. < to go up a half step, > to go down a half step.

I’m beginner, sorry.
I’m thankful.