Confirm and alert boxes are intended to show off a message on specific javascritpt events such as onLoad, onUnload, onClick, onMouseOver, etc. Read more about javascript in the post you made elsewhere, where I pointed you at the available resouces, as for specific info about alerts here: www.pageresource.com/jscript/jalert.htm
Aler boxes ------- used to display an output message Confirm boxes -------- usually called on existing a function call or a break from loop,condition and returns true or false depending on buttons pressed.. www.w3schools.com and read javascript tutorial