How do I create a new folder in my yahoo email without spam being sent to it?

I know how to make the folder, but everytime I make one, all this spam crap automatically gets sent to it instead of my bulk mail folder. I only want email from one person in my new folder.

How do I create a new folder in my yahoo email without spam being sent to it?
See http://help.yahoo.com/l/us/yahoo/mail/or... and http://help.yahoo.com/l/us/yahoo/mail/or... .