Log into your dashboard. You can do that by adding “/wp-admin” behind your website url. ( ie www.YOURWEBSITE.com/wp-admin.)
Enter your user and password.
Click on “Add New” under Posts.
Name your post blog post in the field under “Add New Post” or “Edit Post”.
Enter your blog content in the blog field. It is the bigger box towards the middle of the page.
Publish your blog when you are finished.
Want an image?
Click on Set Feature Image and select an image.
Remember after you change anything on your blog, be sure to click on update.
To view a more in depth tutorial for updating your wordpress blog, please visit http://en.support.wordpress.com/my-blogs/