I am trying to add a second email address to a user in sbs 2008 but i cannot find any option to add more than 1 email address. Any suggestions on what i should be doing.
In the Exchange Management Console, open the user's mailbox. Recipient Configuration -> Mailbox -> username -> properties
In the user's Mailbox Properties dialog, there's a tab for "E-Mail Addresses". Under that, you can add another "SMTP Address". You can also select the default FROM/Reply address in that space.
You can modify the policy-generated email addresses on individual recipients as ewwhite suggests but I highly discourage it.
Modifying individual email addresses on recipients can create problems for you later if you try to make broad, sweeping changes to organization-wide address properties. You're better off creating a group (hidden from Exchange address lists) with the correct alias for the "secondary" email address and making the user a member of this group. By doing it this way you keep all your email addresses generated by policy and make future changes (like, say, changing the domain name the organization receives mail using) easier.