Each month, your merchant or retailer will charge your chosen credit card with your monthly installment payment. Your credit card statement shows the amount that was charged along with the merchant or retailer name.
In addition, every 21 days or so, an authorization (hold) is taken for the full outstanding amount of your purchase. These authorizations are not charges but are taken to guarantee payments on your plan. They may show as 'pending transaction' on your statement.
You should see these authorizations decreasing by one installment amount until your plan is paid in full.