You start by hiding all the iframes with css.
iframe {
display:none;
}
In Javascript you set the display of the first IFrame to block and you create a Variable which stores a numeric number which Frame to show (0=first, 1=second, etc)
var iframearray = document.getElementsByTagName("iframe");
iframearray[0].style.display = "block";
var visibleFrame = 0;
Then you make a button, with an onClick event.
<input type="button" onClick="hideNext" />
And at last you make the Javascript function to show the next Frame
function hideNext(){
iframearray[visibleFrame ].style.display = "none";
visibleFrame++;
iframearray[visibleFrame ].style.display = "block";
}