You'll find this post in your _posts directory - edit this post and re-build (or run with the -w switch) to see your changes!
To add new posts, simply add a file in the _posts directory that follows the convention: YYYY-MM-DD-name-of-post.ext.
Jekyll also offers powerful support for code snippets:
def print_hi(name)
puts "Hi, #{name}"
end
print_hi('Tom')
#=> prints 'Hi, Tom' to STDOUT.
Check out the Jekyll docs for more info on how to get the most out of Jekyll. File all bugs/feature requests at Jekyll's GitHub repo.