Video And Photo Size

I am making a video on my PC.

I use Movie Studio 8.

When I want to insert a Image I make into the video but I want it to be the same size as the video I know the size is diferant.

My video is 720x480 so I make my image 720x540 pix.

but after I make the video and it plays the part with the image it is some what skinney and tall.

What am I not doing?

 

You need to crop the picture to 720 x480.

 

Well this is what I ment.

I know a Graphic Image uses Square Pixels.
And I know a Video uses Rectangle Pixels.

And I can see this because if I open a 4:3 Video that is 720X480 and put a Graphic Image on it.

The Graphic Image will not Fill the whole screen.
I will see parts of the Video in back of it.

This is how I know the 2 sizes are Diferant.

So if I make a Graphic Image and I want it to be the same size as my 4:3 Video that is 72X480 what Pixal size should I export it as?