Use a CSS Class uhhnoi

Tell us what’s happening:

Your code so far

  h2 {
    color: blue;

<h2 class=
   "red-texte"> CatPhotoApp</h2>

<p>Kitty ipsum dolor sit amet, shed everywhere shed everywhere stretching attack your ankles chase the red dot, hairball run catnip eat the grass sniff.</p>

Your browser information:

Your Browser User Agent is: Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36.

Link to the challenge:

In the section of your post that says, “Tell us what’s happening” you should enter a description of your issue so we know how to help you.

mebbe typo?
red-texte = red-text

as @Xiija said, you have a typo in defining your class.
But bigger than that, is the fact that you have not defined nor assigned that class to any html element.