When you create a contact in Pooltrackr, they will be immediately created in Xero.
When you create an invoice in Pooltrackr, the invoice will be sent immediately to Xero, with all line items. The invoice will be assigned to the linked contact, and the line items will be assigned to the linked sales account.
You can connect your Pooltrackr product accounts to the relevant account in Xero. When an invoice is pushed through, the line items will be assigned to the linked sales account.