The first page when you go to create a hub is only for the title and keywords. Hit continue, and it will take you to a page that says what is expected of hubs. Hit continue again, and this will take you to the page where you can create the rest of the hub. There will be a default photo, text, and comment capsule. Hit "edit" on the text capsule to be able to insert your text. You can add other capsules by mousing over where you want them and clicking "add here" and then the type of capsule you want, or by clicking the type of capsule on the right-hand toolbar, which will add a new capsule to the bottom of your page.
I personally recommend that you write all articles in a word processor or notepad document to save on your hard drive first, just in case something goes wrong with saving it online. Hope this helps :).