How to animate a .PNG file?

If you use LoadImage, there will only be 1 frame -- the whole image.

Use LoadAnimImage. Make sure your image frames are all horizontally aligned. In other words, the dimensions of your image should be 14400 x 262.

img=LoadAnimImage(filename, 180, 262, 0, 80)
then
DrawImage(img, x, y, frame)