Javascript on-click code run from within an xmlDocument() in asp.net?

[KathyB]

Hi, I'm creating my first (so please be patient) web app in asp.net.

I have a mainframe.aspx and within that a leftframe.aspx and
rightframe.aspx.
The leftframe holds some variables and has a button to load the
appropriate xmlDocument into the rightframe.aspx.

My question:

The xmlDocument is transformed with an xsl stylesheet and I need to do
two things:

When user clicks the Start_timer button within the xmlDocument, I need
to capture the datetime to an element in another DOM or within that
xmlDocument itself. Could I somehow have that happen in the left frame
page? Or whatever!

The other thing I need is to do is when the user clicks the End
button, save the xmlDocument to a string and save it to a db field.

I'm almost clear on the .net (server) javascript (client) big picture.
But just can't get my brain around how to accomplish the above. Any
guidance appreciated.

Thanks,

Kathy