1. ) From https://www.centeringhealthcare.org/ , locate "My Portal" at the top right hand corner
2. ) login (with your account information)
3. ) click the  "Products" on the blue header
4. ) select your desired products and click "Add to Cart"
5. ) choose your desired quantity and click "Proceed to Checkout"
6. ) confirm shipping address and shipping options and click "Continue"
7. ) Payment Method: if you have an invoice number and wish to pay through that, choose the option: Purchase Order, otherwise proceed with paying with a credit card. 
8. ) An invoice will be generated