if you have a text box on your main form, name it username. In your
vb code, once you've verified the id & password, open the main menu form, set username = id.
might look like this:
if userid valid and password valid then
docmd.openform mainmenu
forms!mainmenu.username = forms!loginform.userid
docmd.close loginform
end if
now on your mainmenu form you have the userid.
good luck
Kevin