Let say GOOG today $620, you sell GOOG puts $600 for $3 (10 contracts) so you profit $3,000 and you buy GOOG puts $590 for $1 (10 contracts) you pay 1k for it so as long GOOG over $600 by expiration you profit $2,000 if GOOG fall to $550 your worst case you will lose 10k. Read about bull and bear spread