Problem with username

i recently open a wordpress account. A friend of mine
that uses wordpress opened me a blog, the thing is
that he opened a sub-account on his account by mistake.
So he transfered the account to my email, because i don′t
have an account.

Now the blog is online, the thing is that it has no user because
when i tried to make mi username, the signup page rejected me
saying that the blog already existed.

So i was wondering how can i create the account with the name i want
and keeping the blog.

Thanks for the help,
Ines