What size does the overlay file have to be?

Green screens are made out of two files.  A jpeg background and a png overlay. These are whatever size you want your photos to be (in most cases, you will make these as either 4X6 or 6X4 at 300dpi., so 1200 x 1800 or 1800 x 1200) The PNG overlay should be saved as a non-interlaced PNG (transparent where you want the photo to show through).

What are the keyboard shortcuts to resize and move your photo position in Green Screen?

To Move the Position use the ARROW KEYS.  Up, Down, Left, Right.

To Rotate use the Z and X keys.

To Resize use the N and M keys.

To Center the image, use C or right mouse click.

Where can I purchase a Green Screen backdrop?

We use green screens from "Back Drops to Go". We have a partnership with them to get a discount when you purchase a green screen if you're an Infinite owner. You can visit their website HERE.