UPDATE: As of July 1, 2013, the 20% Text Rule on ALL Facebook timeline cover photos has been removed. Feel free to go nuts with that text!…
You need a cover photo that represents your business or community pending the type of page you have setup. Cover photos can be anything from a real photo to a photo collage to a crafty display of your products and services, etc.
They display as 815 pixels wide x 315 pixels tall on the page (w: 815px X h: 315px). You would want to upload an image that size for it to display properly. If you upload an image smaller than that it will be stretched to fit that space and it will look horrible and unprofessional.
Although it shouldn’t be too much of a problem, try to save your files for web when you are manipulating these files for online viewing. If your file is more than 250 kilobytes, it will slow down the page’s load time dramatically.
Here is an example of the image sizes and dimensions required for a perfectly fitted Facebook business page.