How to state rank? There are 10000s of ways.
(porcupinetree did state rank though)
Tbh, only reasonable question you asked was how to write a band 6 response. For this, your resources are stuff such as excel success one, and the marking criteria. The marking criteria is obvious - You need to look at WHAT is required to get that maximum mark. You may need to practice writing responses whilst actually looking at the marking criteria.
Almost all of the time (some actually quite ridiculous and don't, like 4% of what I encounter), does success one give a reasonable band 6 response. This is because typically they overwrite, meaning no information can ever be lacked. They also avoid extraneous information to the question. So this resource is usually for figuring out just the content, rather than depth of response (of course, 3 small body paragraphs reads like a mini essay).