If you log in to the site (the Author Login link is on the very bottom of this page) you will be able to edit it and all of the other existing articles. You will also be able to create a new article and make other changes to the site.
As you add and modify articles you will see how your site changes and also how you can customise it in various ways.
Your home page is set to display the four most recent articles from the blog category in a column. Then there are links to the 4 nest oldest articles. You can change those numbers by editing the content options settings in the blog tab in your site administrator. There is a link to your site administrator in the top menu.
If you want to have your blog post broken into two parts, an introduction and then a full length separate page, use the Read More button to insert a break.