If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Grab as many acorns as you can to earn a golden acorn. Golden acorns can be used as ammunition against your enemies or to progress through the game. Toss Blue Ptero your golden acorns to reach the quota (bottom-left bar) and clear the level.Watch out for enemies and obstacles though! Your health bar is on the bottom right.