REQ: Help with popup window....

I am a confessed novice with Dreamweaver MX & web design. I am
looking for some help in creating a popup window, NOT a popup message,
on my website.

Here is my idea. I have one of those calendars with a different
message for each day. I was thinking of creating a popup window that
would display the current day's message which would be activated when
the user first visits my site. I would eventially even like to have
Previous & Next buttons at the bottom.

This is probably pretty advanced even though it sounds simple. I
would still appreciate any help anyone can lend or just point me in a
direction.

Thanks!!!