Today class is about masking....
It so complicated!!!
And, i fool by those keyframes!!!
F5 is to continue the frame
F8 is to create graphic (picture that wanna make animate)
F9 is to open the 'actions-frame' (example like type stop();)
WOW.... It so blur~
Making the mask is not easy too!!!
After creating the layer,
then at the layer there right click it and choose 'mask'!!!
The mask layer must be above the normal layer~
If not it cant work!!!
to make the layer size same as the size of your picture/content
just at the grey side simply and will see 'size' at 'properties'
from there at the 'match' choose 'content'!!
Then it will same size as the one u want!!