Data Access Pages

Hi Folks

I'm struggling with the syntax in Data Access Pages (ms access 2003)!

I wish to populate two fields automatically on selecting any item from
a combo box! ie. If the user selects an item from the combo box a date
field is populated with the current date and time and a flag field is
set to "Y"

I am a complete newbie to DAP but have been building complex ms access
databases for many years (since version 1.0)

Can anyone either point me to a suitable example or show me the code
required

Please - I've been struggling with this for days!

Ta