Thanks for the answer.
I did. I have searched in the forum. I tried http://www.mydomain.com, mydomain.com, mydomain.com/, http://www.mydomain.com/, ... so I'm lost, it looks like an installation bug, because it is so simple that I can't make a mistake.
Reinstalling again:
* deleted all wp_ tables from the database
* deleted every file from mydomain.com/wp/
* chmod 777 wp and wp-content
http://mydomain.com/wp/ shows the installation:
* Sub-directories
* Database name / user name / password / localhost
* mydomain.com as domain name
* email
... and I receive a green DONE with no errors.
I can access the blog with the link in the page, but it shows no grafics or css... and the title link points to:
http://com/wp/mydomain
What I'm doing wrong?