The very best method as prescribed in the link is as follows:
• Select your co-op source: Your Gateway. (This is a number; the Key Code that you will use to designate leads destined for this Co-op. You will want to record this number for your records.)
• Enter a short description of your co-op in the Description field provided.
• In the Assignment Type section, choose either Shares or Signups. It is very important that you choose the correct Assignment Type.
• Click the Create New Co-op button to return to your main SFI Co-op page, where you'll see your new co-op listed. Click the corresponding Key Code in the list to access the edit page for your co-op. From there, you can add co-op participants, view co-op URLs to use in your advertising efforts, and more.
• Once you add your participants/affiliates, your co-op is ready to go. Simply begin advertising using one of your co-op's URLs. The system will automatically rotate and assign results generated, per the method you've chosen.