I thought that backing a team to cover the spread meant that after that numerical handicap had been taken into account at full time if your selection was ahead you win.

The dividend is normally just under $2 (due to the bookies taking their cut) and if after the handicap there is a draw your stake is returned

Eg. Hawthorn +6 ($1.90)

If Hawthorn win or lose by less than 6 you win! If Hawthorn lose by 6 your bet is refunded. If Hawks lose by more than 6 then you lose.