How do you make a login box and a sign up box for my email service? And can I make those transparent?

I dont do this. but I think that what you need is MySQL. An your host must support that and it can make a database basically of your members. An do all of what you need.

<script language="javascript">
<!--hide
var pass = password
var tpass = prompt(what is the password?)
if (pass == tpass){
www.page.com
}
else{
www.errorpage.com
}
//stophiding-->
</script