Thanks for your answer.
1- where do I find the background image exactly ?
2- the banner I mean is the traditional 728 x 90 px banner you can put on the header.
3- Would that be the same with a simple forum based on bb press instead of the entire buddypress plugin ?
Do you mean that Newscast is a bit outdated now and that I would need to switch to an other theme ? I am running magazine types of blogs.