how do I use apple pay with a credit card?

i added a credit card to my apple wallet. i want to make a purchase for something where i need to use apple pay to text someone money. but whenever i try to send money, it tells me i don’t have any funds in my “apple cash”. how is that different from apple pay? i can’t use a credit card to add funds to apple cash, but i don’t want to use apple cash, I want to use apple pay. so how can I send money over text with a credit card?