Create a new file under _posts following the convention for the name:

year-month-day-post-title.markdown

Add new images under static/images. Don't forget to use the same path when you link them in your posts. For instance:

Run the local server to verify the post looks good:

$ ./localhost

Go to http://localhost:4000 and check the home page.

Publish your blog in GitHub running the publishing command:

$ ./publish

Go to purplicious.github.com to see the changes.