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.