Using your login information, access the WHMCS admin section. Go to the dashboard to access every feature related to invoicing.
Adjust the invoice configurations, such as numbering, currency, and tax settings, to suit your business needs. Define the terms and conditions to be included with each invoice.
Search for an existing client or establish a new profile within WHMCS. Fill in the client's name, email address, and additional information as required.
Choose the items or services you wish to incorporate from your catalog into the invoice. Indicate the quantity, price, and any relevant discounts for each item or service.
Check the invoice details to confirm accuracy. To create the invoice, click the "Generate Invoice" button in WHMCS.
Choose the invoice's delivery method, which can be email or PDF. Send the invoice to the client using the method you have specified.