On your Main Dashboard, hover above your name and click "My Payouts". Once the payouts screen has pulled up, you can click & request a "Total Payout" (button).
You can also click on the "Available Payouts" tab, to request individual campaign payouts. The "Paid" tab will show your history of completed payouts, along with a details button to see the breakdown.
On this page you'll also notice your Tier Achievement scale, showing your total units sold for the current month. This will automatically add you to the tier that you qualify for on a monthly basis!