hhart… YES!!!! That did the trick. Thank you very much. Sometimes one is too blind to see.
topic solved
varkeychaya and tlara8354… thanks for your comments. No. both of your hints remove the header completely: the header picture AND the blogtitle. I want to remove the TITLE ONLY, because the name of the blog is imprinted together with a logo in the picture. If I activate Blog title, it doesn’t look right.
I was afraid of someone writing this. As stated in the post, I don’t have a clue about PHP editing. Can someone at least tell me which file I am looking for ? And what line I have to look for ?