I’m intimidated

OK I have the blog setup. Do I start with a page or a post? What’s the difference? Where’s the help?
I looked at themes, there’s enough info to sink the Titanic, but none on how to work my new toy in the very early stages.
I think I made the wrong choice. I’m sure this is a wonderful system, but I haven’t the time to spend trying to find all the answers. I want the docs that actually tell me step by step what I need to know and do.