go to the 9th rune and then go to the left. you will see a big withe thing. in there right in the middle between 2 trees you have to just sit and wait. dont do anything other than sit there for 30 seconds....keep this message alive!
a star makes you easyer to lvl up. AND HERE IS HOW TO GET IT: when you reach lvl 100 you get a star, and then when you got the star your lvl resets to lvl 0 and you start over. but as i said bafore its easyer to lvl up when you got one. and then you need to reach lvl 110 to get star number 2, 120 for star number 3 and on.... hope that answer your questions :)
the yellow birds is on time, you need to be fast, and know everything you can do. in lvl 1 you cant complete before you completet 2, 3, 4, and maybe 5. in those lvls they will give you very inportant information ps. the green birds will fly away when you double jump