3 problems/questions

1. On homepage (under youtube video), where does this ranking comes from ? Can’t find it in the block or the HTML code of the page on wordpress

Please check the plugin settings page in the admin. In the bottom section you can define which pages the plugin has to use to attach the different content to. My guess is that the ranking page links to the homepage.

2. On homepage (sidebar on the right) -> Top 10 actuel -> Is it normal that nothing is displayed ? Do i have to wait for first games for rankings diplayed (but then why question 1. ?)

This is by design, the shortcode function that you use here, does not have a fallback like the ranking page (which will show a list of all users if there is no data). Once the first match has a result and you have completed a calculation, the list will contain the user names.

3. On http://www.monpronostic.be/mes-pronostics/, why does team names are displayed twice ?

I can’t tell, because I do not have an account. But if I have to take a guess, then I think that you miss the flag images for the teams. You can either upload the images to the correct folder, or hide the images with some CSS:

img.flag {
    display: none;
}

(PS you can answer in french if you want ;))

Nope, sorry. Je ne parle pas français 😉

It is best if you do not change the CSS files because the WordPress update system will overwrite your changes after every update of the plugin.

You can add your styling to the Custom CSS field (Appearance 》 Customize) or you can create a child theme for your theme (sounds complicated, but is very easy).