This needs to have a few formats or sizes because it will be printed and used on different things.
It will be used on a DVD / CD disk (4.75" / 120mm consider it is printed round so all the corners are not printed, use 300dpi).
The other format is about the same size (4.75" square or similar size rectangle, use 300 dpi) to print on the DVD cover, an ebook cover, brochure, and other bigger marketing.
A smaller version for the website, business cards, etc.
The grapic could be irregular shape so 1 version is a .png format without a square or retangle background so it can be placed on top of something else without the white background showing.
There can be a .jpg with a square or retangle with a white background to print on a white paper.