All you have to do is drop a button design-time-control (DTC) on your ASP, call it cmdSave, and the proper subroutine for the click event is:
<%
sub cmdSave_onClick()
do something
end sub
%>
If you do a response.Redirect in the subroutine, make sure to put the sub at the top of your page above the first <html> tag, otherwise the page will start writing to the browser before the redirect hits, and you will get an error.
I use the same structure with DTC listboxes optiongroups, etc:
<%
sub listbox_onChange()
do something else
end sub
%>