Help to Blogs! 🙂

Hello @ Blogger, I’m writing a blog right now, unfortunately that doesn’t want to be the way I like it. 1. How do I get another background? Especially when I think of the blogs of the Spamtastic4, there is a picture of the whole background, how does it work? 2. I have chosen a blog with pictures. this uploaded….but one of the pictures is only 1cm high? although the original photo is almost 1MB large and has a dimension of 3200×1200 pixels. 3. I would like to the first picture likes to make centered over the complete text, but no matter which picture position I choose over the adjacent dropdown menu, it always remains at the top left. Thanks for help. Greeting Martin