Fisheye lens applies an effect to the layer as if it was shot with a fisheye lens on an SLR camera.
Import photo to the canvas and tap ②Filter from ①Tool selection window .
Tap ①Fisheye Lens .
Drag and adjust the sliders of the ①Radius and Distortion as you like. When finished, return to canvas with②✓button.
And you're Finished.