[jQuery] SimpleModal (probably something really stupid)

I am using the jquery simplemodal code to display a div on a page.

I am pretty much calling .modal(); on the div, which has a class on
it, and I'm styling up that class - some issues though:

1. How do I add a close button.  Have seen that I can add a closeimg
style - but I can't get anything with this class to appear.  I figure
I need to set the closehtml property to something but haven't figured
out what.  As this is embedded in c# I might have stuffed up my string
escaping.
string termconditions = @"$('#" + pnlMemberAgreement.ClientID +
"').modal({ closeHTML: ''});";
I also tried <a href="#">Close</a> instead of just '' - but either its
making no difference or I can't figure out what quotations to use
within my c# string.

.simplemodal-container a.modalCloseImg {
  background:url(../App_Themes/Images/Ecommerce/x.png) no-repeat;
  width:25px;
  height:29px;
  display:inline;
  z-index:3200;
  position:absolute;
  top:-14px;
  right:-18px;
  cursor:pointer;
}

2. Whilst the div is made visible, it sits under my content - its not
being overlayed over the top, nor does it have a background colour
going on.  I grabbed from the sample site:
.simplemodal-overlay {
  background-color:#000;
  cursor:wait;
}

.simplemodal-container {
  height:400px;
  width:600px;
  background-color:#fff;
  border:3px solid #ccc;
}

Is this an additional option I need to set?

3.  The div is not acting like a modal object - I can still click
other buttons and stuff on the same page and leave the page!

4. I'm confused with the styling.
what do I need to put on my div so that the right styles get applied
to it - or should I be doing this in options?  ie. I have my t&c
inside a panel, and I tried putting a css class on that for the
container part, but where do I put the overlay - or should I not have
to do this.

It sort of looks like the basic modal example does what I want it to
do.. but I can't figure out what I have missed in my implementation of
it :(

I pretty much have this in my c#
string termconditions = @"$('#" + pnlMemberAgreement.ClientID +
"').modal();";

and want to apply some basic stylings so that the frontend guy can
take over but it will do what its supposed to

Thanks for any assistance!