press Command + T to enter the Free Transform Mode, and transform the image inside the mask to get a result you like.I got stuck after Command + T, i dont know how to transform the image inside the mask to get a result you like. Sorry my english not good ^^

Select the Water Fill's layer thumbnail, press Command + T to enter the Free Transform Mode, and transform the image inside the mask to get a result you like.

Hit the Return key to accept the changes.When i follow this step nothing show/change on my screen. ( Still blank Dark )