I like to find my backgrounds on stock photo sites because I'm able to search for I want and they stand outside the standard backgrounds that Twitter offers. A 'crop and resize' pop-up window will appear where you can enter your required proportions in the 'width' and 'height' container. http://Www.Salespider.com/selfserve/clickurl.php?id=55833&url=aHR0cHM6Ly9Xd3cuQmlvZ3VpZGVuLnNlL3JlZGlyZWN0LmFzcHg/dXJsPWh0dHBzOi8vbGF1bmNoaGFwcHkuY28v