I wanna add a picture that shows in my blogs header. Is it possible to show an image in a slide show in the header, when I publish a new post?
You can use jQuery for creating a slideshow with your lates posts. You can either develope it yourself or look for either free or paid plug ins. I know that themeforest.com sell some but i also think it is possible to find free plugins. As you didn't say what blog you have (WordPress, joomla...) it is hard to point you to a plugin for you blog