How do I find the add frame tool

[Chiamaka5E55]

I haven't used photoshop in a while so when I tried to find the add frame tool for an animation I couldn't find it. Instead it has duplicate selected frame which is not what I want. 

[JJMack]

When you click + icon in the frame  animation panel the frame that get added is the composite of the layers visible in the Layers Palette.  Change the visibility of layers in the layer palette to change the content of the frame added. You can height any frame in the panel and change its content by changing which  layers will make its composite image. You can also change  layer position, opacity and effects in frames. This animation has two layer the top one has a layer mask to mask the lower layer clouds and the top layer content is not linked  to the mask. So when the  top layer JJMack content is moved the logo is mask for the lower layer clouds.  I moved the upper layer content is the second new frame added  and had tween add frames between the first and second frame. Both layers are visible in all frames.