You can start by inviting your friends.
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http://multiply.com/info/faq?category=GeneralHow can I find people I know on Multiply?
To see if people you know are already on Multiply, click Invite on any page. You can search your e-mail address book, or you can enter specific names, e-mail addresses or Multiply user IDs, to find people. If you already have at least one Multiply contact, we'll list some of the people your contacts are already connected to in the "People you may know" section towards the bottom of the page, since chances are you know some of those people too.
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Or you can just go to the site of the user you would like to add, then click 'Add As Contact'. The link is below the default picture of the user.
thanks :) 
