Importing image into working file in CS6

Hi there, I'm a newbie so forgive me if this is an obvious problem!

I'm working on something in Photoshop CS6 and I need to import an image (it's a PNG) into it (I currently only have the background complete), but it won't just let me import an image. Here's what I'm doing:

File> Import.
It gives me the option to import "Video Frames to layers", "Notes...", or "WIA Support", but not just an image.

When I press File>open, it opens the image as a brand new project (in a new panel along the top).

What am I doing wrong!??
Any help is greatly appreciated!
Thanks so much!

All you really need to do is to File->Open the .png file. Copy the contents by selecting all (Ctrl + A, Ctrl + C). And then in the other project/psd file you just paste it as a new layer with Ctrl + V.