Well, first you would grapple and pin your opponent. Then, if you had sufficient strength, you would hurl him as if he was an object. I'm sure there's a page somewhere for determining distance hurled by mass and strength of hurler.
Since giants often do such things for fun (Go for distance! Go for distance!), a scoring system has been included to help you score the quality of a throw:
Score 2 points for every meter your opponent travels before striking a surface or being. Add 15 points if initial surface contact inflicts or facilitates damage independently of hurling(spikes, fire, oil acid, etc). Score 1 point for every meter your opponent bounces after impact, measured from point of initial impact. Score 5 points for every opponent struck by the hurled opponent. Add 25 points for every opponent killed in such a manner. Add 30 points if your opponent comes to rest in a location which would inflict additional damage after bouncing. Add 50 points if your hurled opponent dies.
Example: A giant hurls a halfling 20 meters through the air (+40), striking a partymember(+5), killing him(+25). The halfling lands in a pool of oil(+15, facilitation) after striking the partymember and bounces 5 meters (+5) into a bonfire (+30), and burns to death(+50) for a total of 170 points.
Optional: Points scored may be awarded as bonus experience to the hurler.