Drop-down list next to the attachment paperclip icon in the open message
window and choose item => attach them.

As an alternative to BillR's advice, you can also copy those contacts to a
separate Contacts folder in, for example, Public Folders.  You could also
create a separate contacts folder in your mailbox and share that.

Thank you both for your responses, but copying the contacts to a different
folder and sharing that folder doesn't work.  When the person trys to open
the folder - it states that the folder could not be opened.  I thought I read
something somewhere that only the default main folders could be shared and
not folders that have been added.  Is there another work around or did I do
this wrong.