How to make a competition 'active'?

Hi, 

I'm trying to add a match and under 'Match Setup' and I'd like to make 'show only active competitions' 'yes'. If I do this the only active competion in the dropdown is last season. I'd like this current season to be an option.

My quiestion is, "How do I make a season an active competition, so that it becomes visible under this feature?'

Many thanks,

Darren