One year of support is included with each paid
license purchased from Six Apart - the cost depends on the license.
If you are using Movable Type installed at Yahoo! activated via your hosting control panel there, this is a free license which does not include support from Six Apart. If you do wish to have support for that version, you can purchase an annually renewable support package, which gives you access to the Help Ticket System. You can find information about purchasing that support package for the Yahoo version here:
http://www.sixapart.com/movabletype/support/yahooAlternatively, you can use this forum for user-to-user support.