When you edit an article in Joomla, underneath the ArticleText you will find buttons like Image, Article and Read more. The Cook component will not display these buttons by default for Rich text fields.
How to display these buttons: edit file admin\dom\html\form\input\editor.php
Change line
$html = $editor->display($this->dataKey, $this->dataValue, $this->width, $this->height, $this->cols, $this->rows, false);
Into (false -> true):
$html = $editor->display($this->dataKey, $this->dataValue, $this->width, $this->height, $this->cols, $this->rows, true);
If you want to display only certain buttons you have to change some more code, just check the Joomla category and article components in the administrator part on how to hide/display buttons.