I'm building a forum based site using Hyperboards.Then wouldn't it be more appropriate to use their support system? Unless members here are familiar with how that particular service works, I doubt anyone will be capable of helping you.
They give you option of inserting codes in the forum to customize itIf there's no obvious way to modify content within the head element, then its unlikely that you'll be able to add any meta elements, but again, this is a point you should raise in their support forum.
Mike
For the record, 'accessibility' generally refers to providing content to those with a variety of disabilities. Issues include: the behaviour of assistive technologies such as screen readers and aural browsers; concerns regarding the effects certain content may have on colour blind, epileptic, or dyslexic users; the impact a feature may have on users with motor impairment, and so on. The Accessibility forum is not a generic dumping ground: that's what Other is for.