This is just how I like things, quick and simple through CLI (command line) using gifsicle for free.
gifsicle --colors 256 --delay=200 --loop banner.gif banner-page2.gif > banner.gif
banner.gif = the first page of the banner
banner-page2.gif = the second page
--delay=200 ms to switch between the two
--loop=it goes back and forth between the two pages forever
banner.gif=the resulting animated gif.
There are many other options and features but this is a quick and easy way to get an Animated banner going.