@fx: For details color options, upgrade to Catch Everest Pro Theme.
1. I would like to return the bottom bar with the name of wordpress but smaller and change the color (black and white).
— To change the background color or footer site generator, You can add the following CSS in “Appearance => Theme Options => Custom CSS” box.
#site-generator { background-color: #000; }
2. Then I need to place a banner (image) just below the menu (throughout).
— For this you need to upgrade to Catch Everest Pro Theme, where there is Featured Image Option.
3. I also have a problem with the color of page titles that are black (not white).
— You can add the following CSS in “Appearance => Theme Options => Custom CSS” box.
`.widget-title, .entry-header .entry-title { color: #fff; }
4. And last, I always have a white box below the blog (i need to remove it).
— I don’t understand this one.