Both parents and kids can enter rewards. When you enter a reward, you can specify how many points and which children the reward is available to. When your kid has earned enough points for a reward, they can request to redeem it. Once you approve, the reward is theirs (it's up to you to follow through)! A child can enter their own rewards for their Wishlist in the Stridepost app, but they still need your approval to redeem them.
When your kid adds an online reward, they can't edit the amount of points the reward is worth. They'll just be asked for confirmation. For family rewards, kids are allowed to type in the amount of points they think it's worth, but you can always edit it later.