Okay, i got it. Normally you see on other sites that they let you publish your content at very first step. But hubpages is different.
At first page, you can enter your title, and can have customized url of your post, and provide your hub a category and set up some ads related options, then click on continue, it will lead to you another page which will encourage you to write original content, then hit again the continue(submit). Now this is the display where you write your content, just edit the suitable capsule and write there.