You can either flip the entire canvas or individual layers, so isolate whatever you wanted to flip into its own layer. If it already is, simply select the layer in the layers panel. This puts a box around the element that allows you to rotate, stretch, shrink, and twist the image. To get to free transform, you can:  Select "Edit" from the top bar, then "Free Transform." With the right layer selected, press Ctrl+T for PCs or ⌘ Cmd+T At the bottom of the menu are the options to "Flip Horizontally" or "Flip Vertically." Choose the one you want to flip the image:  Horizontal flips switch the right and left side of the image. Vertical flips switch the top and bottom of the image. Once you're happy with the transformation, you can hit enter to set the image how you've edited it. You can also double-click inside the transformation box to end it.

How would you rephrase that briefly using Chinese?
选择你想要翻转的图层。 输入“自由变换模式”来控制图片。 右键点击图片，打开翻转选项。 点击“回车键”确认翻转。