updating field with data from other fields

i have an access database....it has first name, last name and a field for
email address of every entry, but the email address is empty...i need to
somehow concatenate the last name, the first initial of the first name and a
hard coded literal that will be the same for all....

i.e. JonesG@xxxxxxxx

the only thing different will be the lastname and first letter of first name

what's the best way to do this...?
.