The way most online poker sites will work is by taking payments through many different options. Don't let that frustrate you, because it still might be possible to conduct a wire transfer, possibly through Western Union, or use another e-wallet system. This means they are not going to accept your US based PayPal account or any US credit or debit card. Many online poker sites will simply try and avoid the United States banking system entirely. Although it was never illegal for a US resident to play online poker, the poker rooms themselves were attacked through their payment options. This is simply because the laws were very hostile to these poker sites even just a year or two ago. A number of poker rooms in 2023 are not going to be very accommodating when it comes to helping arrange a deposit for a US player. The first will be your actual location, i.e. The payment options offered to you will depend on several factors.
Basically, each poker site is going to offer you a number of different methods by which they accept online (and sometimes offline) payments. There is no way to play in any real cash or real money game until you actually have some cash in your online poker account. Making a deposit at online poker rooms is normally how you get things started.