To create your own blog post (all users by default have a blog on WSO) click your username in the top right corner of the website. You should now be on your profile page, with an option to "View My Blog". Click that button. The next page will say you have not created any blog entries, and underneath it will give you the option to "Post a new blog". Click that, and away you go!
Alternatively, you can select the "Create Blog Entry" drop down option under the "Forums" menu at the top of the site.