Hello,
I am completely new with scrivener
Because I am making a lesson book I need to create a lot of colored text blocks. So far I have only found the litle a in the toolbar and highlight under Format in the top menu. But this is not working. I do not want to highlight. I like to create colored boxes. How do I do this? 
Thanks for any support
You can create a one-cell table and apply a background color to it.
More options, including how the manual does it, here: How to make a box like in the Scrivener User Manual - #22 by slothinker
This post has a list of links pointing to other threads that discuss how to implement advanced formatting, such as call-out boxes, in ebooks and print media.