You can sign up for a new one on the outlook.com site but I have no idea how to migrate an existing hotmail.com address to outlook.com.
I can't even get to the new outlook.com with my hotmail.com address; it was only after creating a brand new outlook.com address that I was able to see what all the fuss was about
You should simply be able to do it by: logging in into your hotmail account and going to http://outlook.com while still logged in. After that, go into mail "More mail settings" (click on the upper-right gear) and choose "Create a Outlook alias" if you want to add e-mail aliases @outlook.com
But now that you already signed up for a new account it may not work straight away...
