On the left-hand navigation, you'll see a + sign in a dotted box. Click that and you'll be taken to the Sales Channels page.
This is where you can select a sales channel to sell on.
To sell on the A.C. Moore Marketplace, click the "Connect to A.C. Moore Marketplace" button.
You'll be presented with a modal, where you can enter a shop name, choose your shop currency and your PayPal email address.
Note: If you are already selling on either the Zibbet Marketplace or Stitch sales channel, then your shop name will be the same, and therefore can't be edited.
Click "Get started" and the A.C. Moore Marketplace sales channel will be turned on.