This temporary Starter account, Explorer, was automatically created for you.
A Starter account can do almost everything a normal account can do such as Liking and Favoriting photos, but it will expire after a while.
To rename this account and keep it for yourself just enter your email address in the header dropdown above.
It's that easy.
I'll update my processes when 500px has an API and Posterous gets it going...in the meantime I'm blogging here: http://remotephotography.posterous.com/