Transfer it to the Gallery and Click the screenshot button.
After the screenshot, a pop up will be shown in the screen, click Share.
Wait for the confirmation that will appear on your screen.
You can check the status of the objective in the Settings>Contest menu.
Comment your screenshot to Kim's Garden's Facebook account and don't forget to tag 3 of your friends with the hashtag #KimsGardenBloomingNow. Remember your tagged friends must download and play the game.