Your username must be the same as in your UAO campus, that’s what you have in you e-mail address before the @uao.es .
It is free, and easy. You can do it starting from here so you will not be asked to build a new blog. If you are forced to open your own blog, it doesn’t matter, BUT KEEP IN MIND THAT POSTS MUST BE IN THE COMMON BLOG FOR THE SUBJECT, NOT YOUR OWN.
Then I will invite all of you to join the blog as contributors, and you will be able to post. You will be told when it is time to start posting, but by now, get yourself a username.
If you want to know WordPress works, you will find plenty of information on the internet. But I have written and example post with the intention of helping you in learning how to write.