By creating an availability group you can offer certain products or categories of products only to select customers. Those assigned to the group will see the assigned products when they are logged in, in addition to your normal products when they visit your store. Other shoppers will not see the assigned products.
Enter a name for the group and click Add.
Three new tab headings will appear at the top of the screen: Customers, Categories, and Products. From this point the process is the same as editing an existing group.