how to insert text over image

Hi Marc, Ellen,

Thank you for all you help. Last issue has been resolved :).
I would have two more questions, this time concerning Zeitreise & Ubud themes :

1- How can I insert text over un image, in a page ?
2- How can I create a colour banner (grey for exemple) with text on it (something like colour boxes, but simpler and uniform) ?

Best,

Elena