editing the tag line in the header

I am trying to edit ie change, the tag line in my headers.
I have gone into Appearance—headers—
but the tage line does not turn up.
When I found a place to change the text of the tag line, (by accident)
it did not rollover into reality.
Would appreciate some clues, thank you

http://www.greenhalghgardens.com

I am trying to remove ‘It’s all about the soil’
and replace it with ‘Designing for beauty and habitat’