Delete old emails in gmail from a specific date.

I can perform a search with the following criteria in gmail.
before:2011/11/20 AND in:anywhere

How can I go to the next step and delete all those mails.
Google search for delete old mail from gmail don't return any thing useful.

Idealy I would like to create a filter with some search useing just the "before:" operator.
before:2011/11/20
I keep getting a Please "fill in some search criteria" message box.
To fix this you don't use the filters
Gmail creates a link for you to delete all the old mail, it is not very obvious. It appears just above the first message in the list of messages.

"All 20 conversations on this page are selected. Select all conversations that match this search"

If you are running short of space you could always buy some more from google
https://www.google.com/settings/storage/