Benny,
If you had backed Fremantle at +11 , you WIN 10 units.
If you basked St Kilda -11 , you lose 10 units.

I actually participated in this match on spread betting with Sports Acumen.
I had $100 per point on Fremantle at +10 so picked up $900 profit.

The spread betting books usually do not offer a price but just a line.
For example, St Kilda -14, Fremantle +10.

My advice on this form of betting is to try and back the outsider if you think they can beat the spread. backing favourites and giving away start is treacherous. On many occasions last year, the outsider won the game comfortably without needing the start.