I can't seem to figure it out!!

I am trying as hard as I can to learn how to make this blog thing work!!! So, I need to know a couple things! How do I layer my header? I want to put a picture or some writing, or both, in the cute frame in my header.

Also, can someone please explain to me how to make it possible to arrange my pictures that I post and be able to write in between them so that it is not always just the pictures and then my writing?

I am so confused!!!